The point of sitting on a stool is that you have to use your core strength to sit up straight, and using that core strength reduces all sorts of pain in back and neck.

I didn't start doing that (sitting on stools) till I had been meditating for a long time, so it wasn't that different than sitting on the floor in half lotus position, which I had extensive practice doing.

I've been doing it for >10 years now; I will confess that when I have a meeting in a meeting room with proper chairs, I do really enjoy the chair back. It's all about using your body in a variety of ways.