You compare two completely different things. Counterplay is something people came with and if Riot decided to change it's definition they simply can, It's not a sky that we can't do shit about. Also I've never seen any official definition of counterplay and looking at Riots actions sometimes makes me thing their designers themselfs are in disagreement. Meaning you believe in your definition of counterplay that you probably heard long ago and I believe in my definition.
Counterpicks do exist, however good thing they became less apparent with recent years I think. About team composition it's true, but I think it shouldn't decide the game.
And about ADC or rather marksmen being reliable. They are, but not in a sense that you think. When I say that something is reliable I mean you cannot avoid it's damage or other effects without getting out of their range. Maybe statistics say that they not a problem, but that because of two factors. There's always marksman on both teams what means it's always marksmen against other marksmen and second reason because of their ridiculous importance they always focused which can lead to completely destroying ADC and them having weak farm and KDA. You're one of very few people that argue and defend this class while I see a lot of people wanting something to change finally.
And lastly. My point that other champions that still could be played around, but got reworked anyway while marksmen didn't still stands.