It was false impression, my friend...Since one can be durable and still have external pressure points to affect (your thread about pressure points was pretty good, by the way), one may be durable and don't have external pressure point which are similiar to those of normal humans (Thing, Ult. Colossus- though I was under impression that both of them (I'm sure about Ult Colossus) have weak spots on outer surfase of their bodies, which are their eyes) and another one can be durable and have altered nervous system (like Diamond Emma and to lesser degree-current 616 Colossus- I'm not sure whether he belongs to type two which still can be hurt by special chi technique (proven by Iron Fist and Gamora- although her feat with Thing looks more PIS to me than IF feat where it was actually use of chi)) thus being totally impossible to be affected by pressure point attacks.