[crashdancer]

>The end user of the kernel -- user space -- never sees any of this

I mentioned it because despite that difference I don't think it's practically much different from a developer perspective. Big changes are still about as organizationally difficult for kernel developers to do. If someone wants to deprecate something that a lot of other people are using and it's a lot of work, then they still have to convince everyone to go along with it, get them onboard with the new API and help out with removing the old API, etc. That's the actual hard part, sometimes it can be made easier by providing a shim but often it's not.

>the userspace API never breaks

This is an aspirational statement, not a rule. It has been broken lots of times. The userspace API in Linux is not just the syscalls. Effectively it encompasses every single thing a driver does and exposes in some fashion to userspace and a number of other things as well. Whether that be ioctls or other non-standard interfaces exposed by block devices, sysfs entries, procfs entries, other pseudo filesystems, netlink events, configuration files, low level userspace libraries like libselinux and libseccomp et al that technically aren't part of the kernel but the kernel developers encourage everyone to use them anyway, util-linux and other utilities of that nature, you get the picture. This stuff changes all the time and it's not even possible to keep it all stable forever because it's such a massive amount of code.

>You're implying this is equivalent to GTK and Gnome intentionally breaking API with every major release for every applicaton that uses those libs. It is not.

Yes you're correct that it's not exactly the same but I'm implying the exact opposite: The GTK and GNOME changes are actually much less of a problem! You can have many versions of those libraries installed at the same time. You can't easily use many different kernel versions at the same time.

>Frankly it's a bad faith argument.

It's against the guidelines of this site to make this kind of statement. And quite frankly it's very uninteresting to respond to. You can make your point without this.