It isn't about whether or not the lighter fighters could be heavyweights.
It's about relative athleticism. All divisions have it.
Jose Aldo is fantastic, he does crazy, mindboggling things in the cage when he gets in there. Same with guys like Anthony Pettis.
You see a woman's MMA fight and it LOOKS like a joke.
I saw Marloes Conenen, supposed to be this top tier pioneer of women's MMA, get taken down and mounted repeatedly by Carmouche who wasn't even training a full year and looked every bit of. She had no idea how to punch, and spent entire rounds punching Coenen from mount like you punch when you are 4 years old and don't even turn your fist over.
It was absolutely disgraceful, and these were "top 10" fighters.
There's some sort of disillusion that I must hate women because I'm not PC and don't delude myself into thinking that I'm watching high level mixed martial arts when they step into the cage. It's like watching a drunken bar fight 80 percent of the time, the other 20 percent is watching Cyborg smash some poor girl's face open in 2 minutes or watching Ronda throw someone and armbar them.