Except he is not even a fighter to begin with.
His gapcloser has 18 sec cd at lvl 1, and 14 sec at max level, that's prob one of the longest cd for any gapcloser he needs to aa or stack cdr or ofc, killed somebody to even have the possibility to use more than once in any given teamfight.
He is immune to slow when running yes, but have you tried landing anything other than slow onto him and see how fast anybody can delete him just like how fast he could wipe you if he caught you distracted? You don't need an abundance of cc, you only need 1, then 0.5 seconds of team effort so he can go back to his base.
That's pretty fair tbh.
He is only remotely a threat under 2 conditions:
- He sneaks up to your arse and at least hack away half of your hp without you knowing, nor did anyone landed a cc onto him.
- He got so fed early it no longer matters.
Which both of these scenarios are your fault, a behind Yi will die to a super minion 1v1 that's how bad he is, if he is actually fed then by all means, he should be rewarded.
He has so many counterplay options on the table it's not even funny. Yi's fine.
EDIT: Also he has 0 cc in his kit.