They probably work better since you don't have any of that post processing bullshit in a monitor.
The smaller sizes of monitors means most people will have them on desks, spaced for the best compromise between M/KB access and visibility or detail. When you're farther away from the screen, like with a TV, there is more space to grasp your controller. Your hands and the controller won't bump the bottom or front of a desk and you won't ever be resting your forearms on top of one.
Speakers that provide a sense of space (meaning, not desktop speakers) are also more tedious to use with monitors. Sitting so close to the monitor means the speakers will be blocked by the monitor.
Isn't HDR mostly still crappy on all but the pretty expensive monitors? Many modern games have nice HDR or at least look better with it on.