I don’t know, but I’ll tell you a story about no hands squats. Mikhail Koklyaev once did a no hands squat with something like 660lbs. He loves to do things to please the crowd, and that’s just something he decided to do for some showmanship. Sam Byrd saw this and thought “Holy shit I want to do that.” I later watched Sam squat 645lbs in the Animal Cage with no hands. Pretty awesome, especially considering Sam is like 100lbs lighter than Misha lol.
Maybe other people were similarly inspired? I dunno, more likely some dumbass crossfit guy did one with like 135 and everyone followed suit. Let me know if any of them are doing it with 600+.