Because people just hate his name in general "Yasuo" They find it a Meme now and find it funny to ban him usually, that's just how it is sadly.
Most of my friends ban him saying "Better ban Yasuo!" and nothing more then that, I usually ask "Why ban him?" And they never say he's overloaded or broken/useless.
I really doubt Yasuo's small scale rework will do shit as people just don't care and will ban him either way probably.
I've played A LOT of games vsing a Yasuo as well as having him on my team and I barely had a toxic one, so I'm curious why people are saying "ALL Yasuo's are toxic!"
Sad to see a champion getting reworked over a Meme and people thinking he has no counter play when he is the champion I defeat the most in lane normally with how simple his kit is to me.
I'm actually curious why Riot doesn't do anything about people on YOUR team banning Yasuo from you, just because of a Meme. But whatever. Just wanted to get it off my chest, a shame Yasuo will be gutted and destroyed with his rework most likely just like Rengar over some people who refused to learn to play around him.
Edit: The fact people ban Yasuo from you and laugh about it & call him a abomination, I've noticed they are usually more toxic then Yasuo will ever be.