but what if we are talking about blind pick?
The argument started about the new 1v1/2v2 map. At this point, no one knows whether Riot will use the traditional blind or draft picks methods. No one knows whether or not people will be able to use the same champions. So it very well could be mirror-like.
Although, the whole premise of "what if you get counterpicked" is flawed. The game mode is about first blood/ 100 minions/ 1st tower. There will not be a late game where one champion is a super hard counter to the other. In addition, we will be seeing the same sorts of champions battling each other. If it is for ad carry, there will be two carries battling, not a carry vs a bruiser. Sure, Quinn has a blind and could be considered OP in carry v. carry duels, but if lane countering was so powerful then everyone will scramble for Quinn and their bot lane would always win.
Basically, 1v1 is an actual test of skill. People don't need to pick the same champion because they have different preferences and it doesn't really matter in such a short gamemode. And I'm sure that after a best of whatever match, the best at a position will come out on top.