External, non-distro-maintained package repositories have been common for ages. I was still in elementary school, so my memory is a bit fuzzy, but I'm fairly sure downloading and installing individual packages was something I did too in the 90s. And fundamentally, any system that is open enough that "you can compile whatever you want on the device" is an option can also have binaries distributed.

Sure, the Linux ecosystem has not prioritized binary compatibility as much, so doing so has been harder, people culturally expected "use existing libraries" more than "just bundle everything", but as you note that attitude has shifted to and it always was possible.