It's just fucking stupid.It's not even challenging to knock someone up on yas especially if you have a knock up comp. A 18 sec CD at 40% CDR, he can use that shit twice in an extended team fight. Yas has a lot of bull shit in his kit and this isn't even his most annoying thing. A champ with an overloaded kit like yas should at least have a CD on his ult.
Edit: stop talking about yas not building CDR, that isn't the fking point, and also he has very viable options for CDR but the main thing is the 30 sec base