Integration into our tools, backporting fixes, doing release engineering, tracking upstream changes, triaging and resolving distribution bug reports, documenting usage and troubleshooting, configuring defaults and best practices, a whole lot of testing, etc.

As I said, there's a lot of work that goes into a distribution (I probably haven't covered most of it) that most people don't think about. And that's assuming that a distribution is going to be passive about something as core as a filesystem -- which we wouldn't be. So we'd be working with upstream on development as well, which is more work. So saying something like "it's supported on distribution X" when that distribution doesn't even provide official packages for it is a massive stretch. It might work on distribution X, and you might provide independent ISV-style support for it, but it's not supported by us.

I appreciate that the sort of work distributions do isn't well-publicised (mostly because stability is hardly a sexy thing to blog about, and we don't rewrite things in JavaScript every weekend). But there is an incredible amount of work that goes into making distributions work well for users, and there's a reason that many distributions have lasted for so many years (there's a need for someone to do the boring work of packaging for you).