YEP - When a Lab, or Golden, or even a Shepard bite, they generally do just that - bite.
Pits and other dogs with genetics of fighting breeds lock on and try to kill. That is the whole point, and is why we don’t hear so much about other breed bites. It isn’t that those others don’t bite, it is that they bite less often, and when they do, it is almost always less damaging.
You are almost totally correct. Pits do lock on and hold, that is the problem with them and where most of the damage comes from. As far as other dog bites go, they can be pretty damaging. Also, they can be just as deadly at times. It is true that you do not hear of other dog bites as often even though they do bite just as often and probably never will.