It's not "the solution", it is a solution.

It is the easiest solution, requires no research or technical ability, and will not have any left over cruft from the hours of customizing.

The same goes for windows, I know people who reinstall every 6 months just to keep their system clean and working optimally.

> I wish the Linux desktop was implemented more like a user extension on top of a rock solid base server layer.

I would argue that the Linux kernel is that server layer, but let's not open that can of worms.

Maybe Fedora Silverblue is up your ally. All the apps, including the desktop environment are containers.

Or if you really want an actual hypervisor you could try Qubes, but that is not for the faint of heart.