Linux is super fragmented (and generally has been historically).
If more people in Linux agreed to develop, use, and support the same distro–similarly to how most of us use the same kernel–then that distro would probably be better than Windows and more people would move to Linux.
The problem with that is simply that what counts as good will vary from person to person.
I think there’s a baseline that Linux developers need to take more seriously. The PopOS people are good reference, especially their upcoming DE.
Imagine you had a basic desktop; top bar, dock and desktop widgets.
Each of those is a different app and each app comes in 4 different flavors: “Fast but ugly”, “Pretty”, “Tinkerer’s dream” and “Well designed but under developed”.
Sounds great right? Just pick whichever ones you like best. But along the way, things that would be considered “requirements so basic we don’t even need to state them” are not met.
So you value pretty and get the pretty versions. But each of them was developed by a different team, each with different opinions about what “pretty” is. Your desktop doesn’t have a cohesive look with colours and fonts mismatched in a way that no monolithic project would ever tolerate.
So you grab one pretty app, and two tinkerer’s dream apps. You can make them match yourself! That’s the power of Linux. You put a week of work into bringing your desktop up to this default standard, fighting a mountain of faff along the way. Each app uses a different language for their code and configs. Each app supports different features. You find yourself wishing they followed the “well designed but underdeveloped” app, but it hasn’t had an update for years.
Finally, your desktop is ready for unixporn… as long as you don’t open your file browser.
Well yeah, but that’s what standards are for. Look at Wayland. Outside of GNOME being a bit slow, all the major compositors and DEs like KDE and Hyprland have agreed to implement certain common desktop features that every desktop should have along with the Wayland protocol itself. Then they go their own way.
So it’s not really as you say. There is unity in development beneath the heavy diversity.
Except they are
This is a bad example bc it’s opposite to what you say. You haven’t set a universal theme. Theming is commonly supported across desktops to some degree. You can get all your apps to have the same look unless an application forces its own (which would happen even in a homogenous Linux world). Some desktops will do it for you, but if they don’t it’s still as simple as install a universal theme, apply the Gtk version, and apply the Qt version. My understanding is soon it will be even simpler once a few more Wayland standards get adopted.
We already have the best ecosystem. It literally could not improve functionally