https://www.pcgamer.com/queuing-for-a-specific-role-in-overwatch-could-hurt-spirit-of-the-game-says-jeff-kaplan/

Putting together a balanced team in Overwatch has always been a problem. No matter how many times you plead for two supports, two tanks and two damage dealers, someone will always upset the apple cart by stubbornly picking their favourite hero no matter what. That's led some to propose a system whereby players pick a specific role—tank, healer or DPS—before queuing up for a game, guaranteeing a reasonable team composition. In an interview this week, game director Jeff Kaplan said that the idea is a "good starting point", but that he isn't keen on putting it into the game.

Kaplan says the community has proposed two versions: an "honor system" whereby you queue as a particular role but you can switch out when you make it into a game in order to respond to enemy picks, or a rigid system that locks you in to your chosen role. "Neither is fully satisfactory to me,” Kaplan told Kotaku, adding that the more rigid system "hurts the spirit of the game".