I think wnt2bBeast hit the nail on the head. You see pros doing all sorts of things, but in the end, it's the heavy compound moves that got them to that size. Maintaining muscle is so much easier than some people think. Especially if you're enhanced, eating and resting properly. You only have to train so hard to maintain your gains.
Squats are better, no doubt. I'm not impressed when my peers jump onto the leg press and do the rack, panting and heaving to get up two reps, and act like they're gods. I'm more impressed when I see someone squatting ass-to-floor, with good form, for 20 reps.