"I wont play supp no matter what"

{quoted}

you can specialize one role ( specialize one champ is straight up trolling imo ) while be flezible enough to not feed in lane. I'm bad at top, but I can still use nasus or irelia without feed 100% of the time

Nah, you can specialize one champ if you want. Look at ICU, or Trick or Nightblue. Its trolling when its trolling, and you intentionally act in a way that is detrimental to the team, in lobby or in game. If you just wanna play nothing but annie mid then go for it, but if you don't get your spot and your champ its YOUR responsibility to act like an adult and opt out of the game. Its not on your random teammates to accommodate your every last wish, if they want to do them and that prevents you from doing you then Riot gave you the handy little dodge option to use.

Is it ideal to specialize just one champ? Um... no... ohmagerd does foos banned muh pony!!!! NUUUUUUUUUU!!!!

But if you want to its fine and dandy as long as you act like an adult about it. I make a new one trick account every season to try and one trick a new champ to diamond every year. I pretty much play nothing but that champ for about 200 games. I let people know ahead of time though, and it helps when I tell em to op.gg me and list a dozen accounts that tend to be extremely persuasive. But if I cant get my deal or some one really wants what I want I let the team know I'll dodge and to pick all trolly picks, like all support comps so they can target ban the enemy team next lobby when I'm gone.