The problem is that the game has no movement acceleration, so if you flashed someone they’d just spam AD crouch, movement abilities etc. A silence/cripple could work, but again you still have the issue of AD crouch spam it would just end up encouraging fth even more
What could be interesting is if they reworked flash as you say, got rid of FtH and replaced it with a lasso or something which crippled the enemy for half a second or something but McCree also couldnt move but both could shoot (or something along these lines, I haven’t really tried to balance it out).