Support main here.
In the end, you can’t blame the 5th DPS because it’s not kindergarten rules where whoever picks first gets the role. Everyone has an equal amount of responsibility towards the team and can change at any time.
And you can win with even the weirdest setups. At times I’ve lost with double healer and double tank comp against pure DPS simply because everyone on the enemy team played so well and our tanks weren’t experienced enough. And I’ve won games switching off healer because the team was so scattered that simply going Soldier gave us the same amount of healing but much more pressure.
The problem isn’t the initial picks. The problem is refusing to switch afterwards.
Sometimes you’re just gonna go up against a comp to which your hero is useless. I’ve had Widows refusing to switch despite getting repeatedly murdered by a pure anti-Widow comp and killing nobody through the entire game (Genji / Winston / D.Va / Orisa / Symmetra / Zenyatta).
And sometimes you get the death lock choke point (Bastion / Widowmaker / Symmetra or Tobjorn or Junkrat / Orisa / Mercy) where there was no effing way to get through without a shield tank and the team would first swap at the last 30 seconds realizing it was the only way they could actually play the game.
My way of dealing with it?
I try and win every game. If we get crushed repeatedly and no one is switching hero, I usually stop playing healer and just go for something fun. Because it’s not fun to die repeatedly trying to keep your Genji alive against a full tank comp with no front line.
People usually don’t complain. But sometimes they do, lol. “Who was playing Mercy? Pick healer.” They won’t hear any suggestions to switch themselves, let alone pick healer instead. It’s the finest level of hypocrisy in QP.