@Robby:
No one is saying remove the obstacle entirely. But it's always been kind of BS that some mons are made 100% unviable because of ONE move. That doesn't even have to be used on them directly.
Spikes, spider web, poison spikes, leech seed, none of those are nearly as overpowered, and to be effective some of them have to be used multiple times. Flying types are immune to spike, poison types immune to poison spikes, leech seed doesn't get to do 1/4 damage on things that are double weak to it and so on.
When one move is SO overpowered that it singlehandedly requires your team to carry it, requires you to have a counter for it, and all by itself eliminates dozens of monsters from ever being playable… yes, there is a problem with that move and it needs to be fixed.
Don't quite agree with this.
For one, you mention that some mons are made 100% unviable, but even without this move existing several mons are just unviable simply because of their ineffective stats, movesets, typing, etc.
Talking about this like it's a problem of reducing competitive diversity is non-sense considering that the mons that cannot run in the meta right now mostly can't do so because of these other factors. Not to mention that there's loads of mons that are able to be used in a competitive scenario almost exclusively because of their ability to deal with hazards. Something like Natu/Xatu would not be valuable without magic bounce, for example. Or the several mons that can run rapid spin or defog.
So no, stealth rocks is not reducing the pool of mons that are viable. Not to mention also that SO MANY other moves or abilities screw over more mons, like arena trap dug, or pursuit traps, or certain types having rather powerful priority moves + technician, etc.
If a mon is not viable, it's because it lacks the tools to belong in a specific tier, not because of stealth rocks alone.
Then, to further that we have the fact that there are multiple mons who are extremely weak to rocks and, NEVERTHELESS, they persevere as viable pokemon in the meta. I seriously am curious about what mon it is that you are thinking is made completely unviable by rocks, because I can think of several mons weak to rocks that exist nevertheless (fire types like charizard, alola marowak, volcarona; flying types like mandibuzz, landorus, pelipper, mantine, mega pinsir, and zapdos; and probably a bunch of bug and ice types too that I'm just not thinking about right now.)
From there, we can talk about how many possibilities exist in the meta at this point to deal with both hazards and the chip from them. You can use Z moves like z-memento to switch in a mon with a free heal. You can wish pass. And as mentioned even by both of us, several mons exist with several options to remove or counter hazards. So even IF there is the one mon you REALLY like to use but can't because of rocks, you kinda still can. Unless of course you have an entire team in mind that's rendered weak by rocks, in which case the problem isn't the competitive meta being unbalanced, but your team having a particular weakness.
Now, let's consider also the fact that leaving around every hazard EXCEPT rocks is rather an unfair buff to Flying types, who are unaffected by every other entry hazard as well as by terrain effects. There's already a significant portion of seriously powerful flying types in the meta, and nerfing rocks counts as a significant buff to that type and to those mons, who sometimes need that chip damage to be taken down at all. You are right in one thing, no one said to remove the obstacle, but a nerf is a nerf is a nerf, and going from 12.5%-25% chip on certain mons to less damage harms the effectiveness of the move considerably, particularly towards flying-types. (Or the very needed 50% chip on the very very powerful mega pinsir, mega charizard Y and Volcarona.)
And then there's the other moves you mention. Sticky web can also be a seriously damaging entry hazard that can cripple an entire team if not dealt with properly, but it's less common than rocks and that's why you don't seem to care about it. Leech seed can also be a seriously crippling move in the hands of a good stall team, and it's weird you bring it up as being inoffensive when so many people in competitive matches truly, seriously hate stall.
But besides my lack of understanding of this post, balance-wise I just don't agree that going in and nerfing rocks would be ultimately a fair trade. Nerfing a move that single-handedly expands the meta from being JUST about setting up sweepers, that diversifies team compositions by requiring setters and removers, that diversifies gameplay by getting players to account for switching damage and thus discouraging the game from being a constant switch-fest until one player gets the right read… all for what? So that a handful of people feel like their mon can play safely without losing? It sounds illogical. Particularly since it's one of the handful of moves that account for how people play this game competitively, namely the switching out mechanic, and punishes repeated use of that strategy.