You're allowed to just straight up snap limbs in half in those cage fights still? I thought they tightened up the rules to prevent this stuff from happening.
It's their responsibility to tap and not act too tough for their own good. O'Neill definitely had the chance to tap earlier yesterday. It's not like such hyperextension happens in an instant so that people don't get a chance to tap (at least 99% of the time).
I don't recall any rule change related to this. That said, as someone who doesn't practice martial arts I wonder if the fighters crank slowly on purpose to give their opponent a chance to tap, or if it just takes a few seconds to break someone's arm/leg.