Once again, this is not a case of a natural evolution of the metagame. What it is is a clear case of playstyle bias.
You are perfectly fine with Haxorus having the potential to easily 6-0 stall. To you, this is inherent in the pokemon and shouldn't count against it. It's perfectly fine if a suspect helps make a playstyle completely unviable, that's just a metagame shift. Sounds reasonable, right?
But, what if there were a suspect that made only stall viable? For instance, say we were testing a new Fairy/Water mon with Filter and stats exactly like Blissey's except for massive defense instead of special defense. It singlehandedly contributed to the downfall of offensive teams - there was just no viable way to break through the incredibly strong cores it created. Yet, this pokemon is far less potent against stall - it's easily shut down by taunt, status, and phazing and finds nowhere to use its exceptional bulk and defensive typing. It also fits a lot better in a stall team - and because everyone's using it, the natural progression is that ninety percent of the games in the tier become stall v stall.
Sounds fun, doesn't it? I realize that this is an extreme example in some sense, but it's essentially a mirror of what's happening. The only reason that no one is complaining is that bulky offense has a better rap than stall - in the past, when stall was even close to being the dominant playstyle, there immediately followed an outcry for bans and suspects of pokemon that enforced a natural evolution towards a stall metagame.
We find another perfect example of this bias in the relative lack of interest in the recent banning of Shadow Tag. The only user who even seemed to care about it was
hilarious, and it's pretty easy to see why. Gothorita is as cut-and-dry of an example of a pokemon who completely disables the ability to use stall as there is - and given that there's a strong bias against stall being even remotely viable, no one really gave a shit if it stayed. It singlehandedly hard countered and trapped Blissey, Florges, Aroma, Umbreon, Slowbro, and many more massive defensive threats. I see Haxorus as absolutely no different except for one key thing - it actually carries its own weight against offensive teams. That's why in the current meta of 100% offensive teams, you can say "Oh, Haxorus is balanced", because if we do want a meta that is constantly 100% vaguely bulky offense it's not the most broken thing in the world.
Don't get me wrong, I'm not advocating for a meta in which 50% of the teams are stall-oriented or anything. I enjoy offense as much as the next guy, but it's not fair to completely shaft players who do enjoy playing a more stall-friendly metagame just for the sake of keeping a pokemon who is neither necessary nor balancing to the tier.