Bad games happen, of course swapping can be beneficial. What should Sombra have gone? Do you really think it would have won you the game? Was someone toxic toward the Sombra? What could you have done to turn the loss into a win?
I’m not trying to say that Sombra’s not at fault at all or that you are, just trying to picture how much of the loss was her fault.
Anyway, unlucky. Yes, I agree, people should have at least 2 heroes to swap between, it is part of the game. But blaming someone, even if you’re right, won’t help anyone.