That's not exactly true.
Heigh and weight can be both used separately.
If you throw away weight classes, and go solely on height, then it becomes super easy... much like weight classes.
The problem is mixing those together. maybe adding like height ranges that would span over 2 weight classes. So if your X tall, you get these Y and Z weight classes classes.
Dunno man... like I said I don't have an answer... but the question is there and it's a problem.
It's not cool to see someone having that much reach advantage. I mean I'm a big Darren Till fan, but that dude it too big for that weight class. Let's be real.
Or Costa fighting Hendricks ? How is that a thing ?