It doesn't have to be 100%, but nobody wants to invest a ton of time/energy into a project just to hit a wall a little ways down the road when something at the very core of it breaks or becomes unmaintained. Of course it would be nice for users of such projects to help and contribute, but this isn't always practical. Not because the users are being entitled assholes, but often times they aren't even the same skillsets, and I think this is especially true of some of this complicated, low-level UI stuff. If I'm a user of PyGObject writing GTK apps in Python, I'm not necessarily capable of contributing to the underlying C bindings, even if I wanted to be helpful.

This dynamic presents a legitimate problem for pretty much any open source project that aims to abstract away something very complex to enable more developers to use it. Any project that does this is going to have more developers relying on it than are capable of contributing to it.

You should never feel entitled to continued development of a project you don't contribute to, and you should always assess the community around tools you want to use in order to make good decisions. But this doesn't mean you can't be super frustrated if something you rely on goes dormant. I personally avoid using any library/package that doesn't appear to be very active, but nothing is foolproof. Even a seemingly healthy project die can fairly quickly in certain circumstances.