Define “pinch.” No, really. 
The reason I say that is I’m a mom and I’m guilty of gently taking my five year old daughter’s cheeks between forefinger and thumb, but not compressing, which I would hardly define as abusive. It’s something we’ve done since she was a baby. If she said, “Stop it,” I wouldn’t do it, but she runs over to me and yells, “Look, mommy! Cheek!”
If, on the other hand, we’re talking about, “rip your face off” type handling, then yeah, that’s annoying at best and even cruel at worst, particularly if the kid has expressed that he/she does not want it to happen.
When I think of pinching cheeks, though, it’s pretty damn gentle compared to what is described here. People actually do that?