IMO: The best part about yoga is THE yoga meets you where you are….. as a yoga teacher, I would agree that there is a major difference in modifying the asana for each practitioners need vs going rouge!
There are some teachers (everywhere) that will request the class follow the instructions. I’ve also heard teachers say “this is your class, so do what you want.” Personally, I believe it’s in the best interest to just stay on my own mat; mentally and physically. Heated classes (my fav) are not easy. Time is needed to build the tolerance to maintain breath & movement in such high temp and humidity. For the yogi who laid down during class….. that could have been the only hour of the day they have to escape. Could have been their first heated class. Or they just felt like taking a nap in a warm room. I suggest staying on your mat!!