There is a reason why MMA decided to rule against certain things like hitting the back of the neck, eye attacks, biting, groin kicking and such and the reason was that, typicaly, these things were NO as effective as everyone thought and that they just possesed undue risk with no real reason to be used.
Over the man decades of NHB fiighting where ALL was premitted, the number of fights that were WON because of a groin attack or eye attack or bite or whatever were so minimal, so insignificante that you really couldn't justify the POTENTIAL injury to the potential victory ratio.
In other words, the best fighters won regardless of rules so why not protect them from needless injury?
Lets be honest here, with all techniques being allowed, which means ALL people can use them, is their ANY advantage to having them allowed?
Psalms 144:1
Praise be my Lord my Rock,
He trains my hands for war, my fingers for battle !