Yeah, the idea is that you can cause bone growth through creating microfractures or smth like that

It's called mechanostat (Well, the theory of bone growth is called mechanostat, making it grow would be some sort of osteogenic exercise) and if you think "Microfractures" are involved you're mixing it up with muscle hypertrophy.

Not saying you're the one doing the misunderstanding. The guys hammering their faces may not be up on their bone physiology.