The reason your champion might have been banned.
So a lot of people have been upset before when a team member bans their hover. While it's understandable sometimes there is a good reason for the ban.
Mid: If I see a full AD team most likely that Yasuo or Zed is getting banned. Sure it seems unfair but ban phase is not long enough to have a U.N. peace summit with my mid laner. I'd like to so that my team has a good chance of success and no unwilling particpants but... That's not LoL.
Support: Your support got banned ? Perhaps the ADC did not like the idea of an AoE champ in lane. Abilities rampantly going through the wave is tilting. Also it could be that the team needs a tank and does not need support MF.
ADC: ADC pick could be banned because perhaps the gamble of Vayne makes someone feel uncomfortable. Maybe there needs to be some AoE dmg lke MF or some tower nuking with Trist.
Top: Sometimes when you're top lane and you're about to lock in Riven your team might not be okay with the gamble of Riven either being terribly oppressive via a good laning phase or terribly oppressed because first pick Riven might get met by Pantheon or some other cheese.
Jungle: Junglers... Oh junglers... Sorry but I am guilty of the Master Yi ban. I don't want that elusive jungler who appears only at 25 minutes to go berserk. I've been guilty of banning stuff like that hoping for something more to the tastes of a ganking jungler who can apply pressure to objectives and lanes more so than early game Master Yi can.
Pick Order: Sometimes 5th pick Yas isn't something I want to chance. I would rather ban the champion than hope we get it. Not that Yasuo is OP or anything but personally i feel he's annoying as an ADC main. ( ( ( WIND WALL ) ) ) That's just an example though of why pick order could be a reason. Also the argument of "yes but couldn't you just pick his champ for him or could the top pick do it ?" gets shot down when you consider the top picks might already be contested champions.
It's not to spite you or because someone else doesn't think you can play the champion efficiently... It's just that sometimes a game is better off if a ban is used to prevent that thing that doesn't need to be. I've seen some players adjust their pick and carry the game. Adversely I have seen other just troll the game in to oblivion. It's a chance you take when ban a team member's hover. Sometimes it is worth and sometimes it is not.
TL;DR - There are reasons for banning team picks. It's not automatically because some troll is out to get you. Sometimes the team comp calls for something else. Sometimes it's because your "unique" Mordekaiser support sounds terrible to Jinx. Sometimes it's because someone would rather not see 4th-5th pick Yas get sniped by first pick enemy.
supports who don't speak English. Presuming how other people must play the game is just another kind of toxicity."