Legal punches to the groin? Seriously?
Stomping on a guy?
The UFC doesn't allow either of these.

I just can't take a sport seriously that allows a man to swing away at the
head and face of a prone, unconscious human being.
Ref's are usually pretty good about stopping a fight before someone take a lot of damage after they can no longer intelligently defend themselves. Sometimes they do it too early and the fans are in an uproar and sometimes they wait a second or two too long and people complain about fighter safety.