This is not season 2 buddy, almost every champion these days has a CC ability in their kit, even adcs, like wat?!
"Adcs are dead to yi", right, providing they don't have G.A and they're afk farming for 30 minutes solo in a side lane
Pretty sure you haven't played against an adc that can properly space out and kite or a team that knows how to protect its carries, for real.
"Plus he's really fast and can't be touched", meanwhile mf can still outrun you through Highlander, same for draven, jayce, neeko and the list goes on. Trust me, Slowlander isn't as good as you think.
"To CC a champion you need a skilshot and many yi can dodge quite easy" Yeah sure, like Malzahar R, Rammus Taunt/Roll, Maokai's root, Pantheon's stun, Fiddle's fear/silence, Ryze's root yada yada yada, all those abilities involve A LOT of counterplay and need some LCS skill to land, don't they?
And the best part: "He destroys mages". EX. DEE. LOL.

Honestly, do me a favour, I want you to main Yi for like 2 months and spam rankeds with him. You'll see by yourself "How broken" he really is, especially after the recent nerfs. It doesn't even have to be on your main account if you don't wanna climb with this "dirty ass champ" you can do it on a smurf. But until then, PLEASE, keep your opinion for yourself lol.