It's not just about comfort, it's about it not messing up your back long-term.

A bean bag is pretty comfy, but if you work in one 40h a week, your spine will be dust within a year.

Unfortunately the best chairs are even more expensive than gaming chairs. As an example, Herman Miller's Aeron has been rated as one of the best designed chairs for over 2 decades and costs over a grand. Imagine that with gamer tax added to it: basically no one would buy it. So they simply don't make chairs of that quality level to sell to that target demographic, it would not make economic sense to.