That's just not true at all. The reason Linux hasn't penetrated the desktop is because it's not installed by default. Even if that isn't the reason, the GPs preference for reinstalling is certainly not. Switching DEs doesn't require reinstalling the OS, it requires searching your distros app store for KDE, and then logging out and selecting "KDE" when you log in again.
You could even switch between them each time you log in, depending on your mood that day.
No, Linux has poor isolation between the base system and application and third-pardty software and poor backwards compatibility (FreeBSD is slightly better in that respect). The only OSS Posix system that getting it right seems to be Haiku.
This is not how people want it though. The want to be able to install any version of any software old or new irrespectively of the base system. Flatpack is close though.
You could even switch between them each time you log in, depending on your mood that day.