You've simply run into what I've dubbed the Homoerotic Yearning for Dominance Effect or HYDE. This is the ugly side of the Just Enough Kinetic Energy Levels or JEKEL principle. Let me explain.
When MMA 'fans' watch the sport, there is a basic principle in play - it takes a certain amount of kinetic force to drop somebody, throw somebody around. Everyone knows this. It's going to be harder to KO someone when they're bigger and taller than you. For reference, see McGregor vs Diaz I. Against an opponent he did not handily outrange, McGregor's usual one shot left had less kinetic force as he threw it against an opponent with actually better range than himself. This nullified the dynamite drop down effect we usually see as he catches people coming in - it's a hard shot but not a killer one unless the opponent is moving into it. For reference, see Anderson Silva's entire career. Add in Diaz's iron chin and you get the first fight.
Now this can be misleading, because that doesn't automatically mean a huge fat guy is going to win every fight. Roger Huerta kicked the shit out of a giant NFL guy because he's a professional. I watched 145 Nam Phan absolutely starch some giant fat guy that was dumb enough to challenge him in 4 oz gloves. But size does matter when you're going up against a similarly experienced professional who makes their livelihood doing what you do. This is where JEKEL comes in. You need to hit a certain amount of hard to drop a HW, a LW, a FLW. It's easier for a HW to knock someone out because they're huge guys and regardless of how huge you are, you *will* get knocked out if a professional tags you clean on the chin at just the right moment. That's JEKEL. You don't have to hit like Francis Ngannou if you're a FLW, you just have to hit hard enough to drop a guy that makes 125.
Here's where HYDE rears its ugly head. When a 'man' who watches MMA and is a 'fan' of said MMA sport sees fighters in combat, sometimes a funny thing happens. They see a guy like, idk, Scott Jorgensen's vitiligo having ass bouncing around in the cage. Firstly they think as any normal human would, "Ew" but then they think, "Look at this little guy. He couldn't hurt a fly. He couldn't hurt *me*". The reason lighter weight classes don't get the respect from some people is that in order to feel like it's an actual fight, the viewer needs to feel like it's dangerous. They need to feel scared of the fighters involved. They have...HYDE. They can't explain it, other than they just aren't scared of the damage Mighty Mouse can do to them.
I know, it's a bizarre phenomenon and especially hilarious given the level of cans that inhabit MMA fandom who would be wrecked by Mouse, Dillashaw, just about every professional fighter period. They don't generate HYDE. Guess what? The same clowns that regurgitate the same lines about FLW do the exact same thing about women's MMA. What's the common denominator? Is it technique? Cardio? Finishes? Tough, gutsy victories? The FLW division has them. Women's fights have them. But because neither produce HYDE, these fights will never be enjoyed by a swath of the populace that 'just can't get into the little guys'. Theoretically there's literally no difference between them and HW, minus the wild haymakers and complete lack of cardio that gets HYDE lovers' dicks hard. But because the Black Beast could lay on you and technically get a sub out of it, they'll never call for the HW division to be ablolished despite the fact that it's an embarrassment to MMA half the time.
Hope that helps TS.
tl;dr y'all gay