I don't think it's to deadly. Death seems like an uneasiness step if you have already more or less paralyzed your opponent. Like spiking someones head to the ground, break opponents joints etc. You do understand that this is not allowed in MMA, and avoided, unless there is a mistake, especially during demonstrations.
You can only put the opponent in a submission hold and allow the opponent a chance to tap, but not outright snapping fingers, a wrist or arm and other joint manipulation.
there were no rules in the ufc when it started
the people that did well were wrestlers who could take people down and control them
jujitsu guys who could sub people
and heavy handed strikers who could knock people out
and that's exactly who does well now that there are rules
martial arts are more evolved know because it is tested in full contact competitions
hence the most effective techniques are the ones practiced