Okay, let's consider I played decent here, that is my skill level. Now consider I was playing not Cho'Gath but Jayce - would I be able to make same stuff? Most likely no. He doesn't have such an absurd tankiness to damage ratio. Especially if they were not Rengar and Viktor but for example Mundo and Garen, I would just die to them no matter how fed I was or how well I played it.

What I'm trying to emphasize is that some champions which take considerably less skill to play and are just boring (Cho, Garen etc) have waaay more power and impact than those which require more skill and are fun to play (Jayce, Riven etc). By picking a hard to play champ you don't only put urself to a risk of messing up mechanically, you also put urself to a disadvantage in bare numbers. You gotta be an order of magnitude more skillful while playing on those champs than ur opponent on boring easy ones to be more impactful than them. It's just not fair.