Something I've noticed with bjj guys in MMA is when they catch the other guy in a submission. They still have a degree of control on the lock as they go to break, giving their opponent a chance to tap before any catastrophic injuries. Because that's how bjj guys train, even in grappling competitions most of the guys aren't ripping anything, they give their opponent a chance to tap, if they don't then they break.
In MMA it should be different though. It's not like you can concede or tap out right before a knockout punch hits you and gives you permanent brain damage. Why should the bjj guy give their opponent a chance to concede or possibly escape by not ripping the sub. If your opponent is giving you permanent brain damage with each strike, I think it's fair that bjj guys rip the shit out of any joint lock they get. It's permanent brain damage/CTE vs a broken joint.