I've had horrible experiences with McCrees running around trying to be heroes and instead feeding the enemy teams ult charges rather than killing people. I've had low health characters literally just waltz into enemy ults.
It's already rare enough to find a Symmetra in the first place, let her niche be, even if that game of yours with her ended up going south.
If you look at my stats I posted earlier, I do the single best with Symmetra out of all of the heroes I played with, and there's a reason for that.