The division is just old guys knocking out other old guys, or younger guys that barely even have combat sports training like Lewis and Ngannou.
There's rarely anything skillful or athletic about anything you're seeing.
All these greats were vastly better fighters 10-15 years ago. The fact people even believe it's even possible sports athletes are getting better in their late 30s or early 40s, compared to their 20s, makes me laugh. If you proposed such a concept to any other sport you'd be laughed out of the conversation.