There is a difference between saying arguments are worthless and calling someone simple minded.
Banrate is actually quite significant. Banrate in all elos means a few things, unfun to play against, too easy to abuse and overall not balanced well
That's just untrue. Banrate means one thing, and one thing only, people don't want to face them.
That could be because a top laner doesn't want to deal with him.
That could be because they are 50% playrate and someone doesn't want to see them in another game.
That could be because they are 60% winrate and busted as fuck.
That could be because they completely delete the champion you want to play from the game.
Zed hit a ban rate spike then he got nerfed so what is your point?
he retained a high banrate afterwards (something like 40%) before those bans moved on to other people.
He can easily 1v3, when was this refuted?
Well since he can 1v3 so easily even when behind 0/5 in lane he should have an insane winate, huge playrate, and even new players should be doing well on him.
http://champion.gg/champion/Yasuo/top
50.3% winrate, 9.25% playrate, and 115.33 average games played.
http://champion.gg/champion/Yasuo/Middle
49.01% winrate, 7.57% playrate, 126.56 average games played.
Nothing crazy there, experience players are playing him often and his winrate/playrate isn't that high.
Well maybe you don't like champion.gg?
http://na.op.gg/champion/yasuo/statistics/top
50.31% winrate, 9.54% playrate, no statistics for average games played.
http://na.op.gg/champion/yasuo/statistics/mid
48.37% winrate, 7.43% playrate, no statistics for average games played.
once again, nothing crazy there.
Conclusion. Yasuo is pretty fine right now and your afforementioned assertion that he can 1v3 with only 2 items even when massively behind has no statistical backing.