I think it takes up too much screen real estate, and doesn't add anything to the view.
Extreme sarcasm. The Free Desktop organization essentially stopped all development of their old GUI solution for Linux - named X11 Window System, and went all in on developing Wayland, the successor.
Plus, speaking as a former DWM and suckless tools user, it is elitist, and thinks way too highly of themselves - they think their code explains itself (which it doesn't), features are easy to add (nope), and a readable config file is bloat (it isn't).