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.
A bit of ancient history, the early Macintosh operating system & applications were written on Apple Lisas. Native Mac development tools weren’t released until late 1986.