It's a good warmup, 1-2 sets w light weight (25lb) to "activate the glutes" lol
Sitting down keeps the glutes in a stretched position and keeps them from fully participating in stuff like squats or deadlifts. I squat like 10% more after doing them, plus helps lower back from getting injured. It looks dumb af I agree

Using massive weight to deliberately target the glutes is really dumb though, the lever arm is so short at that point youre just crushing your hips & genitals moreso than building muscle.