See I would agree except getting stunlocked is as easy as a morgana throws a random Q over the wall from fog of war. Or a Maokai point and click snares you, even. Then you're just trapped in an endless loop of free, easy to land CC and a lot of the "skill" of these abilities(aiming, predicting, threading the needle, etc) is immediately eliminated.
CC locks are especially egregious when playing on smaller maps like Twisted Treeline or ARAM; there's less room to move and your forced into a teamfight situation where CC always rules.
I wish that CC had diminishing returns of some kind. Like if you were hit with a morgana Q, Moakai's snare would have a reduced duration, and then so would the lux's Q that followed up.
Or even if they just took time to trim superfluous CDR from the game. There is so much CDR in the game that mid game, many champions have 30 to 40%, allowing them to just perma fish with their CC abilities. The windows to punish CC champions for misplays with their CC has drastically reduced, which feels bad as a melee champion who wants to wait for big CDs to be blown before engaging.
When we are in a tank meta or a mage meta, the things that frustrate me as much if not more than the bulkiness or the burst is the fact that they have literally endless CC on top of that which requires you to play perfectly around because their CDs are pretty damn short.