(We've been over this before, the last time this discussion came up on the Distutils-SIG for a previous Metadata PEP a year or two back, but here goes....)

Obsoleting a package is for handling renames and support transitions.  For example, if it actually did anything to do so, I'd mark RuleDispatch as obsoleted-by PEAK, the Pylons folks might mark some version of that as obsoleted-by Pyramid, etc.  To put it another way, marking a package obsolete is part of deprecation and replacement, not an unsubstantiated third-party claim about the maintenance status of an unrelated project.

If a package is *actually* dead, there's no real point to declaring that something else obsoletes it, and certainly no reason to put it in metadata form.  Otherwise, we could have Twisted claiming to obsolete GEvent and vice-versa at the same time.  Which one should an installer believe?  It makes no sense in a standard where the project's maintainers can say whatever they want about somebody else's project.  The scope of authority for automatically-consumed metadata should *only* encompass the project that provided the metadata.