What I mean is: do Arch Linux developers use Arch Linux to develop Arch Linux? Do Ubuntu, Fedora, Debian, and others do the same? Or is it a case of “the cobbler’s children have no shoes”?
It seems obvious, but it may be more complicated than it appears.
I think that’s almost the only option. The distro is everything on top of the kernel, so to make everything work in tune they will need to be in. Specially Arch IMHO, because they usually post on the community page when some manual intervention will be necessary.