Role Queue would effectively mean you'd need to either retool a playlist (say, strictly competitive for this example) or create a separate one. If you retool it, then wait times increase because the game now needs to match people in a role queue for a match where that specific role is needed, so if everyone wants to play DPS, they'll have longer wait times, where as a support might have a very short wait time because fewer people will be playing them. If you create a new playlist, then you're pulling players away from the other one who want to role queue, and now the player pool for each list grows just a little smaller.
Even then, you'd have to lock people into those roles so they don't abuse the system. Players could opt for support to get a faster match and swap out for a DPS later. If you lock the roles, then you'll run into the problem of not being able to change roles with other players (i.e. if someone is better at support but wanted to play DPS, they can't swap out to a support to help the team win, they're stuck as DPS).
I just think it introduces more problems than it otherwise would solve from a matchmaking perspective and isn't congruent with the nature of OW, which is team focused and also revolves around counter picking pretty often.
Giving a teamwide exp boost for making a 2-2-2 comp might be more likely to encourage better comps without impacting the matchmaking or viability of matches after they've started. So, say if the team plays a 2-2-2 comp they get a 20% bonus in exp.
All of this is hypothetical, obviously, as none of us really has any experience behind the scenes, and without player numbers or the data to look at hero selection and player behavior, it could all just be bullshit on my end (narrator: it was).
Still fun to discuss ways to address some problem areas the game clearly has (like why they haven't just deleted Hanzo and Widow from the game entirely forever).
