Linux distributions were always "irrelevant". Linux distros have always just bundled together standard Linux ecosystem components. The "Linux Standard Base" is

Linux distributions were always "irrelevant". Linux distros have always just bundled together standard Linux ecosystem components. The "Linux Standard Base" is just a formalization of this effect, not the cause of the effect. However, I use "irrelevant" in quotes above, because they're not at all irrelevant. It's an incredible amount of work to wrangle all of the pieces of a functioning Linux system and present it as a shippable distro. Anyone who's tried Linux from Scratch has experienced this. This is also why so many distros are "debian-based" or "fedora-based" or "arch-based". Those distros did the hard work of picking and choosing a subset of components that will work together, and building them from source into combinable packages, now all your downstream distro has to do is remix them in some way.