"Trusting" your teammates

This morning, we had a pair of players who didn't use mics. The rest of our team were on mics, and we got slaughtered anyway. One of the two players, throughout the Dorado map, played:

Junk, Lucio, Mei, Bastion, Torb, Junk again, McCree, Soldier, Rein, and then back to Junk again.

Most of the time, they were going out of spawn as a character, getting wrecked, and then switching. The other player in the duo switched, too, but not as often. They were Pharah, and I don't think I ever saw them in the air. Neither of them used an ult the entire match.

When it's our turn to attack, the person who played multiple characters chose Mercy. They had a total of ten minutes playing Mercy in comp. So, the discussion amongst us was based on whether or not we trusted the player to be able to function as a healer.

We decided to give them a shot. You can imagine how this turned out. Mercy got killed immediately, rarely healed, and then started cycling through every character again. We got hammered and didn't even make it to the gas station. I switched to a healer to try to help, but then we lost DPS, and we were basically missing two ult opportunities the entire match.

When the match was over, the person who we were debating about came onto the mics and was livid, saying we didn't know how to play the game and that we were a horrible group of people for talking about their skill and whether we should trust them.

I don't know. I don't think we were wrong to discuss it. Are there instances where you have to consider a player's immediate past performance in how they're going to perform next, and whether or not you need to manipulate team comp around them?