It ain't fancy though. It's a staple in S&C programs.
Gen Pop are still following bodybuilding principles and programs of yesteryear, and think that they need to take breaks between sets. A/A or A/P supersetting is still a rest. It's not compound setting the same muscle group.
Folks can also use the time between squats and deads for Hip CARS, contrasts, etc. The additional work builds density, work capacity, and mobility most folks would benefit. You get it in 50 mins as opposed to 90 mins.
I agree, most people in commercial gyms half-arse it from one exercise to another. And circuit training. You only have to look at the guys and girls who do that it's not most effective for muscle growth. Studies have shown it's great for weight loss, but you're not going to get strong or too much growth from it because it's difficult to maintain mechanical tension for all 6-8 exercises and the multiple rounds in a circuit.
I've found I've been able to build muscle from circuit training, like you say it's great for weight loss but once I'd dropped the weight I started to put on muscle. I'm not huge by any means but have put on size and definition. Some of the guys try to get me to do weights after class but I'm not really interested tbh.
I do see some people cutting corners in the circuit training, the biggest one is not sticking to the clock and sort of ambling over to the next set. I try to make sure I follow the timer to the second (unless i can't get up or something ha ha)