I, too, have been upset about the absurdity of perma-stealth and how it immediately ruins Overwatch as a game, regardless of which team wins, for quite a while.
But I suggest a new approach.
Embrace the absurdity. Since she ruins the match, use the match to get better and enjoy the game again. Instead of worrying about the other 4 enemies or the objective, simply dedicate yourself for every single nanosecond of the match to the Sombra. Simply play “Kill The Sombra” #KTS for the entire match.
I always tell my team before the match starts, “If they go Sombra, I’m going to do literally nothing at all but play “Kill The Sombra” for the entire match”. Now, this is QP only, of course. But so far, I’ve been doing this for 2 days and had NOTHING but positive responses from my team.
And sure enough, if they go Sombra, I go into KTS mode… Do we win? My goal is to not even know… If I am playing KTS well enough, I shouldn’t even know which team is winning. If I’m aware of the objective, it means I’m not focused on that Sombra enough.
It makes Overwatch fun again.
When there is a Sombra, you play KTS.
When there is not a Sombra, you play normal Overwatch and enjoy the amazing game that it is when there isn’t a perma-stealth hero ruining it.
It’s super simple. I highly, highly, highly recommend everyone plays #KTS moving forward in all QP matches.
My personal favorite to use is Tracer. But as Tank, I use D.Va. Support, I use Kiri or Lucio.
And remember, it doesn’t matter if she kills you more than you kill her. What matters is that you focus on her every nanonsecond. The only way you lose KTS is by focusing on anything other than Sombra. You wanna hit that 100% mark where you focus all 100% of your energy on that Sombra.
Good luck and have fun!