I have recently noticed that there is a considerable number of dists which ship with MANIFEST.SKIP and so started to wonder why that might be.
The only use I can see for MANIFEST.SKIP is to rebuild MANIFEST and the only reason for that is to rebuild the dist for further distribution. That implies the dist having been altered in some way, otherwise the rebuild would be unnecessary.
If the dist has an open repository then I would expect anyone altering it to use that as their source (and MANIFEST.SKIP should happily live there). Contrarily if there's no public source then all a contributor has to work with is the shipped code. But in this case there are no other non-standard files to be avoided packaging, so again MANIFEST.SKIP is unnecessary.
Either I am missing something or there's no need to ship MANIFEST.SKIP at all. Probably it's the former. Do let me know.