I often grab the collar right at the back of the neck in some passing situations. Not from full closed guard, but sometimes controlling your partners head by means of a collar grip or a collar tie nogi is a very valid and effective aid to passing guard. It's not like you have to try to rip the guys head off.
I've noticed too, that people are early discouraged from ever touching the back of the head since its cranking and spazzy, but without pulling up on the head I'd never hit any mounted triangles. It has it's place.
Randomly pulling on or cranking any part of the body without knowledge what you're doing or with a specific goal in mind is going to be frowned on or discouraged as a useless part of your training.