Good platforms allow you to build on newer versions whilst targeting older versions. Developers often run newer platform releases than their users, because they want to develop software that optionally uses newer features, because they're power users who like to upgrade, they need toolchain fixes or security patches or many other reasons. So devs need a "--release 12" type flag that lets them say, compile my software so it can run on platform release 12 and verify it will run.
On any platform designed by people who know what they're doing (literally all of the others) this is possible and easy. On Linux it is nearly impossible because the entire user land just does not care about supporting this feature. You can, technically, force the GNU ld to pick a symbol version that isn't the latest, but:
• How to do this is documented only in the middle of a dusty ld manual nobody has ever read.
• It has to be done on a per symbol basis. You can't just say "target glibc 2.25"
• What versions exist for each symbol isn't documented. You have to discover that using nm.
• What changes happened between each symbol isn't documented, not even in the glibc source code. The header, for example, may in theory no longer match older versions of the symbols (although in practice they usually do).
• What versions of glibc are used by each version of each distribution, isn't documented.
• Weak linking barely works on Linux, it can only be done at the level of whole libraries whereas what you need is symbol level weak linking. Note that Darwin gets this right.
And then it used to be that the problems would repeat at higher levels of the stack, e.g. compiling against the headers for newer versions of GTK2 would helpfully give your binary silent dependencies on new versions of the library, even if you thought you didn't use any features from it. Of course everyone gave up on desktop Linux long ago so that hardly matters now. The only parts of the Linux userland that still matter are the C library and a few other low level libs like OpenSSL (sometimes, depending on your language). Even those are going away. A lot of apps now are being statically linked against muslc. Go apps make syscalls directly. Increasingly the only API that matters is the Linux syscall API: it's stable in practice and not only in theory, and it's designed to let you fail gracefully if you try to use new features on an old kernel.
The result is this kind of disconnect: people say "the user land is unstable, I can't make it work" and then people who have presumably never tried to distribute software to Linux users themselves step in to say, well technically it does work. No, it has never worked, not well enough for people to trust it.
[1] Here's a guide to writing shared libraries for Linux that I wrote in 2004: https://plan99.net/~mike/writing-shared-libraries.html which apparently some people still use!
[2] Here's a script that used to help people compile binaries that worked on older GNU userspaces: https://github.com/DeaDBeeF-Player/apbuild
