Mostly thanks Torvalds accepting just about anything into the kernel, not wanting to play politics if someone rolls a kernel with some drivers that are not GPLe

Mostly thanks Torvalds accepting just about anything into the kernel, not wanting to play politics if someone rolls a kernel with some drivers that are not GPLed, and keeps a strict API/ABI stability. Above the kernel it is a wild west, with each "platform" implementing their own stack for anything beyond the core-utils (and those are more likely to be busybox based than GNU based for political reasons).