29 heroes in OW, 2 bans each = 4 total = 14% of the roster.
4 bans can cripple a role. There are only 6 support heroes for example.
1-tricks will get targeted, adding to toxicity.
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1 ban per team would probably be it, but then who decides the ban? Just adds more toxicity... "I told you to ban X !".
Seen this 1000000 times in League when all bans were decided by 1st pick.
If it's a vote process, maybe it'll be a little better, but what happens if it's not a decisive vote?
I do agree that bans could help eventually, but you probably need a roster of at least 40 (11 more heroes).
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I wonder if OW should experiment with a Pick phase. For example, every team can pick 12 heroes, which would mean every player can pick 2 heroes to add to the team's hero pool. Then during the game only those 12 are available, but can be used by any player on the team. So if I add Mei to the pool, all players on my team could access her (if she's not already being played)
Pick Phase might be 3 picks per turn. So after 4 rounds you get your 12 total. Could incorporate a ban phase which would be more fair after 1st round of picks so that one-tricks don't get countered so hard.
Of course this would increase the time it takes to get into games, so it would need to be a new competitive mode. (Tournament Mode?)