And there is such a huge number of these problematic people there, that banning only 10 would barely make any difference. And giving more bans is impossible since it would be too helpful for finding a match with a carrier.
I think you have a good idea. Limit the number of bans to 5 or 10. It would also make the GUI interface easy for Relic to make. I would probably only ban 3-5 people and I play everyday with noobs in ELO hell. But certain names come up and immediately I say "Oh yeah, that is the asshat that starts fights every match." I wont name names here since that seems not cool by site standards. Although this is almost always premade teams. If they start losing they gang up on the non team member for some troll fun.
I do not think it would change your rank much since game 1 is rank 5000 player, game 2 is rank 100....