Dunno WRT policy here, but there are still a few people who use Emacs 21 and XEmacs. With Org they use an earlier version for Emacs 21. I think an XEmacs dev makes changes to XEmacs to support Org, or something, thereby removing some of the difficulty from maintaining Org. Perhaps that is an option with magit.
I know as a 22 user that I can't upgrade to 23/24. I don't know if the Emacs 21 users can or not.
