Well, the main question is why QSS exists in the first place and even is allowed to cancle supression, as that item and especially the supression cancle creates uninteresting binary situation where the opposing champ pick forces you to pick a specific item even if it overall might be bullshit on your champ.
Those supression ults always have the issue that they are quite opressive, but they have to be that opressive as they get straight usless once your opponent gets QSS.
Balanceing around straight hard%%%%ers just is bad for the game.
The second Question is: Why the hell does everyone compare
to
???
Those two are entierly different items with entierly different purposes. Turning untargetable while also becomeing unable to do anything at all, so self CC is basically the opposite of the CC break that QSS/Mercurial offers.
Which brings us to the question that if QSS is for some reason in this game, then why are ad-champs the only ones that are allowed to get an lategame item out of it?