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.
Most often, yes. But there are exceptions. A lot of Ubuntu developers were on Debian in the early days for example. I imagine some still are - there’s a bit of overlap between Debian & Ubuntu developers here and there.
I maintained packages in various BSDs pkgsrc/ports tree, even though I never daily drove any of them, and had them in a virtual machine at best.