here's the deal cruz,
99% of the people I see "lifting weights" in the gym are doing shitty exercises, no doubt, as part of a shitty routine. And 99% of those people are in denial about how bad their routine is. The weight room is plagued with people who don't squat because they jog once a week and that's good enough for their legs... or people who think isolation exercises are the key to building strength and muscle... or that lifting heavy will make them big.
Almost all bodyweight exercises are compound movements (involving flexion, extension, abduction or adduction on more than one joint) that require some level of stabilization, making a bodyweight routine PROBABLY a superior routine to what most ass clowns do in the weight room.
However, a bodyweight only routine is incomplete. There's no way to train your lower back in a compound manner involving the rest of your posterior chain. No significant method of loading the PC. The benefits of stressing the CNS with weights in excess of 80% of your one rep max are numerous and applicable across the board (improvements in speed, peak strength, power generation, coordination, etc. just to name a few).
So when people say "bodyweight is the best way to go" it really irks me, not because I don't like bodyweight exercises (I incorporate pullups, and pistols into my routine regularly), but because it's clear they have never really trained in the weight room.
So, while weight training isn't helping the two guys at your MMA gym, I'd suggest their routines suck more than the iron does. Send them to the strength and power stickies on sherdog, see what they think.