IMO proprietary lags way more because you do not know if your chosen framework (unless it is Qt, heh) will function 5-10 years down the line with minimal investment in updates.
The Linux kernel is everywhere thanks to Torvalds (overly late in the opinions of some BSD devs) declaring the API/ABI sacrosanct, and holding the other kernel developers to that (much to the chagrin of some that want to do hail mary changes for sake of security or ego).
But the userspace above had been reimplemented again and again because the various libs and such are fundamentally unstable. In far too many cases you can even do a x.y.z+1 update without getting some kind of breakage.
Often because someone decided that spec adherence was more important than real life stability, and thus pushed a patch through that altered the API behavior to be more in line with a spec that nobody had complained about for a decade or more.
