No strong opinion on that one, although I wonder though whether it would make more sense to convert all tracking bugs to projects; the current level of support for the blocker/blocked relationship in Phabricator is pretty worthless. Don't know whether improving that is on their roadmap (and when), though.
Thanks, didn't know about that. It would require better support though, IMO, such as a dedicated project type for tracking projects. You could argue that MediaWiki-Gallery is also a component, but with other tracking bugs that gets awkward.