Earlier quoted context omitted.
Y'know, there are some projects that haven't had commits for a while because they do exactly what they're supposed to do, and don't need a bunch of commits. I consider it a good thing when a project gets to the point where nobody can find any bugs and they stop adding features because it has enough of them already. I sure as hell don't want my quick, clean, elegant, productivity enhancing window manager to turn into…
That problem is alleviated by the fact that, for libraries, updates to documentation are commits as well, so even a very stable piece of software still needs the occasional commit to update a FAQ or somesuch. All in all, I've been surprised how well activity meters work when vetting software.
For most software, though, it's true that documentation can always use improvement.