Well, as a standard basis, let’s go with the assumption that roughly half the players of the game don’t play Comp.
Tbh, that number is probably smaller for Comp by a lot, but let’s go with that.
Blizzard please keep classic comp - #52 by JeffreyKaplan
So take the below numbers, and cut them by half.
Here’s one of the earlier statements by Jeff
Competitive Mode Tier Distribution
Puts Masters+GM at about 4% of the Competitive playerbase.
A more recent estimate put it at 8%.
Overwatch 2 competitive rank distribution | Esports Tales
But like said, cut that by half so more like 2% or 4% of total players.
Then we take the amount of Brig players in those skill tiers.
Then throw in that “AntiDive” focused Brig represents about a generous 3% of all Masters/GM players. (Although probably smaller if you factor in the ones who would care and not just play another healer).
Hero Statistics - Overbuff - Overwatch 2 Statistics
0.02 * 0.03 * 100 = 0.06% of players
0.04 * 0.03 * 100 = 0.12% of players
Now stack that against “Bad Queue times” or “Few Tanks that matchmaker within a wide range of SR” and “Continuously losing what few Tanks they do have”.
Which you could easily say could lose the game a bare minimum of 5% of the total players.