The majority of Linux distributions out there seem to be over-engineering their method of distribution. They are not giving us a new distribution of Linux. They are giving us an existing distribution of Linux, but with a different distribution of non-system software (like a different desktop environment or configuration of it)
In many cases, turning an installation of the base distribution used to the one they’re shipping is a matter of installing certain packages and setting some configurations. Why should the user be required to reinstall their whole OS for this?
It would be way more practical if those distributions are available as packages, preferably managed by the package manager itself. This is much easier for both the user and the developer.
Some developers may find it less satisfying to do this, and I don’t mean to force my opinion on anyone, but only suggesting that there’s an easier way to do this. Distributions should be changing things that aren’t easily doable without a system reinstall.
A minimal install like debian base already has a things that may differ from distro to distro. Or are you equating “distro” with window manager and GUI customizations? Even the kernel binaries may differ from distro to distro.
I know what I said. Linux upholds the “don’t break userspace” contract pretty well: most kernels, particularly those from generalistic distros built with modules, are compatible with whatever userspace binaries you throw at them. Major version changes in glibc (or equivalent) is where incompatibilities start, but those happen quite rarely, and you can often still force multiple glibc versions to run side by side.