Because it’s a stupid dominance thing and it has no amount of sexual gratification actually attached to it. It’s just some nonsense practice that’s been made up by porn. There are plenty of better, more appropriate places to cum then on someones face.
It depends on the other person preference, really.
But no one chums on my face. No one.
If theres cum in my mouth, It’s not coming back out. But I don’t always finish guys off with my mouth.
if you’re not sore afterwards, you didn’t have very good sex