It is to be expected that there is a proliferation of different UIs if there is the possibility of making different UIs run on the same OS. The reason is that everybody has a different workflow, different aesthetic preferences, different ways of doing things (e.g.: leaning more toward keyboard, mouse, touchpad, touchscreen). The best thing I remember in this space were the dozen or so X11 windows managers of the 90s. The worst one is the single UIs for Windows and Macs. There are some ways to customize them but not as heavily as it is possible with Linux.
Wayland seems to restrict what's possible to customize but I might be wrong because I have no direct experience. I'm still of X11 because of an old NVIDIA card and frankly I could stay on X11 forever. I know that I'll have to switch sooner or later because of software compatibility. I'd hate to have to buy a new laptop only to be able to run Wayland. It's still good enough to work with me for my customers.