Originally Posted by Anthony342
Then what about leg kicks in general, should those be allowed?
Round kicks can be very easily defended by checking or even just getting inside past its effective range. There is no effective way to defend a sidekick to the knee that doesnt put the fighter in a compromising situation.
Another difference is that a deliberate roundkick to the knee results in the attacker having just as good a chance at a serious injury to their ankle as the fighter on the receiving end sustaining a serious injury to their knee.