Addressing players being allowed to play shit they've never played before in ranked.
How about you actually make use of the mastery system in this way? As it turns out, it literally has no real benefit, instead of it being a form of boasting and bming. I can't even tell you how many games I've lost just because you actually allow this shit in competitive play, hell, I wouldn't even call it competitive anymore. You actually encourage players to try stupid shit, thus they don't get punished for it. First time Xayah, goes 0/11 in lane, but that's ok. She was trying her best, it's not like she would've done better if she actually played a champion she's actually played before. RITO logic 101.
and first time 
to counter someone so what? It's basically the same thing, hit my key skill and then follow up with the rest of the stuff. I main 
but first time 
but then you realize that tanks pretty much do the same thing. Do some engage and lock down a target.