You're still glossing over Widowmaker's one-shots having no counterplay.
There is counterplay to Brigitte. Not being in melee range is the counterplay. If you mean you can't stop it once it starts, then you're in the same ground as "when I get hooked by Roadhog, I die" territory. The counterplay to Roadhog is not letting yourself get hooked. Same for Brigitte. Don't let yourself get trapped in melee range. If you did, you screwed up.