On the other hand limiting it to one hero of a kind per game helps quite a bit. Overwatch had the problem of very static team compositions early on because they didn't copy that particular feature of MOBAs. I haven't been following that closely but I assume changing that helped quite a bit. Of course they might still have some issues because of the small number of heroes available in the game.

Each composition doesn't have to be perfectly balanced against every other either and the system of picks and bans helps.