Don't expect people to switch heros.

A lot of players come into competitive games to play a particular hero in mind and they probably won't want to switch even if they know if it might help the team.

Take it upon yourself to switch to the hero your team comp needs, or just work with what you have. Don't get exasperated over things you can't control, and you can't control other people.

Also triple dps is pretty good. You don't always need a second tank.

If you saw someone pick Mcree when your team already has Soldier + Pharah, you'd probably want a second tank right? Probably, but it's really not that bad.

A good example of this is any team comp with Roadhog. If Hog was classified as a dps, it would technically make any team comp with him a triple dps comp right? He kills things and he can get picks for your team. Just like other dps.

But since he's technically classified as "frontline" or whateverthefuck, you guys don't mind seeing him alongside a Reinhardt or something. So just have an open mind to stuff like that.

Maybe it's different for me since I play in masters+, but multiple dps compositions are really not that bad.