@Fire Fist:
Because maybe Roger didn't take his crew to Raftel?
And Roger is only known person to reach Raftel. People only hear things from what tales other people tell. No one knew that Shanks was an Emperor, and no one but their crews and Buggy know that Buggy and Shanks apprenticed for Gol D. Roger. If people knew that Buggy was on Roger's ship, they'd probably give him a little more credit.
Whitebeard may have approached Raftel and contracted the disease. Maybe that would explain why Roger turned himself in, because he was sick and knew he was going to die anyway. Just like Hiruluk did.
No. You are emphatically wrong.
If Whitebeard had somehow reached Raftel, the Marines, the other Yonkou, the entire WORLD would know about it. Given the kind of effect Roger starting the pirate age had on pirates, you'd think that the news that someone reached Raftel where One Piece is located, oh, the entire reason the world is full of pirates, would be pretty well known. If nearly every pirate in the world is trying to get to One Piece, someone getting there would be known.
Oda has told us that Roger is the only man to have reached Raftel. There is no reason for him to lie to us. If other people have reached it, but never survived, Oda would've told us Roger is the only man to have ever fully explored Raftel - and it would've had the exact same effect.
In any case, Whitebeard having a disease (and not just being old) is speculation, Whitebeard having reached Raftel is speculation, Raftel having some sort of mysterious disease is speculation, Roger having some sort of mysterious disease is speculation - and Roger having left his treasure at a place where a disease would kill all the pirates who arrived there is preposterous… I hope I don't have to explain why.