I guess it's today's NBA, but in the seventies and eighties, guys were killing each other at the free throw line battling for boards, and just regular plays rebounding. Lots of elbows, pushing, grabbing, etc. Alvin Adams was skinny when he first played, maybe not as much as Wemby, but he got hammered a lot. That's just what other bigs did since he was slight of build compared to them.
I remember one play Kareem basically swept him down to the ground like a karate move. No ref whistle on that. That was before flopping. They didn't reward you back then for falling down. Maybe they need to go back to that for flopping.