I beg to differ.
I use RHPs and they work just like the sun...they heat surfaces which then release heat into the atmosphere. This way, you get overhead AND belly heat. I have a 24" high cage, which with the RHP creates a hot spot of 90F on a shelf and the floor is about 82-84.
My problem with belly heat is that when it's used with loose substrates the amount of substrate can drastically change the temperature; i.e., when substrate is moved an inch above the rest of the substrate the temperature can decrease by many degrees. You don't have this problem with RHPs.