I honestly feel like we're not even reading the same story.
Because Rocks is the villain Roger didn't defeat right?
Blackbeard has been alive for 40 years; What's going on in the One Piece world started 800 years ago. The greater conflict is bigger than Blackbeard. Any Blackbeard theories rely on him being the one to topple the World Government, take the title of Pirate King, find Laugh Tale, take One Piece, etc.
None of that fits thematically with anything going on in the story.
Joy Boy and the Roger Pirates are the only ones to have landed on Laugh Tale since the end of the void century. The Void Century that the World Government is trying desperately to hide. The Celestial Dragons live as gods; the D's are the 'enemies of the gods'. They have some deep connection to the void century. I have my theory, but it's not worth going into in this topic. I'll say that the idea that they're descendants of the lost civilization seems far less likely now. Luffy and Teach are not the only two. There's also Law, Dragon, Garp; There was Rouge, Roger, Ace, and Saul;
Luffy and Teach are both D's. D's are enemies of the gods. Infighting among the D's is far less central to the main conflict than the true heir to the will of D taking up the mantle of their original forebear and rising up to challenge the world.
Joy Boy worked with the Kozuki Clan and allies around the world to leave a message for the future. The Minks foretell the coming of 'the new dawn'; That implies the world is now in a state of 'night'; Whatever bad thing that happened is still happening. The world is already under the rule of an oppressive regime.
Let me be clear, I have always considered the World Gov to be the endgame of the series. I've been saying it for like 15 years now. At this point, it's almost a willful misreading of the series to say that they're a passive entity or that they do not present any active existential threat to the characters and the world.
The 'status quo' is not a good thing in the One Piece world. It's rife with corruption. Yes, Roger fought Rocks. Rocks was not Roger's greatest enemy. Roger defeated Rocks. He didn't defeat the World Government. We now know he didn't even try - and we know the reason why.
They were too early. Roger was dying and Shirahoshi wouldn't be born for another 10 years. They were 'too early' as Rayleigh said to Robin. The pieces were not yet in place. So Roger turned himself in, purposely chose his dying works to ignite the Great Pirate Era, to push his successor to find One Piece on Laugh Tale and finish that which he could not. And his unfinished business wasn't Rocks it was the World Government. What you're all suggesting is that Teach will inherit Roger's will and that's decidedly not going to happen. Whitebeard said as much. Whitebeard knew everything. He knew what One Piece was and he knew who the D's were. Roger told him before he turned himself in after Laugh Tale. Whitebeard knew - and he said that Teach isn't the one. Luffy's the one. He's the one who 'brings the new dawn' as the Minks according to the Mink prophecies. He's the one who will 'shoulder the burden of history';
I don't know how anyone can think Teach has any business on Laugh Tale after reading chapter 967. To even mention him in the same breath as Luffy, Roger, and Joy Boy is a terrible misreading of the series and its themes.
There's nothing meaningful in Teach taking over the world. A tyrant already controls the world. You're suggesting that the tyrant who controls the world and has controlled the world for centuries, who caused the world to become in it's current state, is less significant than a guy a little older than Luffy vying for the same goal.
The title of Pirate King is Luffy's goal, yes, but that is not his motivating desire. He wants to become Pirate King because it represents true freedom. Freedom is his desire. Becoming Pirate King is his goal. Blackbeard stands in the way of his goal, but is not diametrically opposed to his root desire. Thematically, it doesn't work. Blackbeard wants the same thing as Luffy. He's not an 'agent of chaos' as some people suggest - and even then, 'chaos vs order' is not a theme in One Piece. Luffy doesn't represent order. Luffy does whatever the hell he wants. He's a 'chaotic' protagonist, so the idea that Teach will claim One Piece or the weapons and make the world a chaotic hellscape is really out of place. Exchanging one tyrant for another at the eleventh hour doesn't work. Joy Boy left One Piece on Laugh Tale for someone else to find. The Sea Kings, the Minks, the Kozuki, the Fishmen, the Shandorans, the people of Alabasta - have all hid the message for centuries so that the right person will inherit the message and the means to achieve victory where they failed 800 years ago.
The person who finds One Piece is the person to inherit that will. Luffy and Teach are vying for the right to inherit One Piece. Roger found it, but he was too early to do anything about it. So he passed the message along. But now the pieces are coming together. Shirahoshi is born. The time is right and coming soon for someone to rise up and challenge the world, to bring the new dawn - and that person is not Teach. Teach cannot be the one to inherit One Piece.
Teach cannot 'possess' all the weapons because, from what we understand, Shirahoshi is not a weapon to be possessed. Luffy is the one who will help guide her. You're taking all of the cool things that Luffy is set up to do and giving them to Teach instead. Luffy and Blackbeard will fight before Laugh Tale - and the one who wins gets to inherit One Piece / Roger's Will / Joy Boy's Will and then use that information, the true history left on Laugh Tale 800 years ago by Joy Boy, written in the Poneglyph language created by the Kozuki Clan, to face the enemy who erased 100 years of history and has ruled this world oppressing freedom for centuries. And I imagine the symbolism of Teach's picture next to Luffy, Shirahoshi, and Vivi's is that he will be an ally after his ambition is crushed.
The 'Great Pirate Era' was a created for a purpose, and it was not to decided who gets to be the next to wear the crown that was foist upon Roger. It should be obvious at this point that the title is a bit of a fabrication. Just as Morgans used the news to create the narrative that Luffy is the 'Fifth Emperor', the world are the ones who started calling Roger the 'Pirate King', a title he never chose for himself. Luffy wants that title for a purpose; it is the means to an end, not the end unto itself. Luffy wants freedom and right now the world is living under the hoof of the Celestial Dragons. If Rocks represents anything, it is that victory at all costs is not acceptable. The manner in which victory is achieved also matters. Roger faced Rocks 14 years before he discovered Laugh Tale and learned the True History and as mentioned. Rocks was an enemy of Roger, yes, but the entity which controls the world was an enemy of not only Roger, but also Joy Boy, the one who left One Piece on Laugh Tale, and all those who protected the message for the future hero who is meant to come along and change things. That's why Rocks was doomed from the start; Why Whitebeard who allied with Rocks and knew the truth of the world, looked down on Teach and saw someone unfit to inherit that legacy. All of those things matter. To say Teach can change the world without the support and help of people around the world misunderstands the message of One Piece and invalidates the efforts of all those people over centuries. Even Roger, strong enough to defeat Rocks, was not able to take what he learned at Laugh Tale, and change the world without all the pieces in place. Because he was dying, he knew he would not have enough time to wait - and so he passed the message along and created the pirate era, knowing that the one who discovers One Piece will be that right person. Someone like him. Someone like Joy Boy. Someone who could make allies of people around the world, the only means by which effective change can ever happen. Just like Rocks, Teach is doomed to failure. He cannot change the world, but Luffy can. The era of Whitebeard? The era of Blackbeard? None of that matters. It's ;like arguing over who gets to sit on the Iron Throne while the army of the dead marches southward.
Roger ran out of time. But he knew the time window for his successor to finish the mission. Shirahoshi would be born in 10 year and take another 15 years to grow up. His allies have helped guide Luffy along. Luffy rising up to defeat the ones controlling the world will not be done alone, but with the help of allies around the world, and through the effort of many who came before him throughout history, including Roger. That's the will of D. Without that, Teach has nothing. Weapons? Gold? None of it matters. Teach doesn't have the single most important quality which will allow Luffy to change the world. And that is why Luffy will fight Blackbeard for the right to become Pirate King, inherit One Piece, and go on to challenge the ones who control the world and stand in the way of true freedom.
I apologize for any grammatical errors and / or redundancy.