Yes.
Fighters simply can't quit of their own volition, and cant really be expected to either.
That's what the corner is for. Yeah, it's to give advice and get your guy prepared, be able to coach them during the actual fight, but most importantly: You're there to step in on their behalf if necessary. Just like each fighter is told to protect themselves at all times before the bell, your first priority should be to protect them when they're no longer able to.
The pay structure of "half to show, other half if you win" likely causes many coaches/handlers to hold out for any hope of a late comeback against their better judgment. They'd rather get 10% of 60,000 than 10% of 30,000 (just an example)
Ethically, I think that's a real issue in MMA culture.
Just my 2 cents