I feel that we’re straying pretty close to a philosophical discussion of “what is the purpose of a sdist” at this point. That’s likely to be a large, and possibly controversial, discussion, as well as likely not resulting in much in the way of actionable decisions. So I’d rather not divert this thread any further for now.
So let’s just say “people have different opinions on what should be in a sdist” and leave it at that for now 
If and when we do have the “what is a sdist” discussion, I think we should start it from the POV of what invariants we’d like to see (such as “any sdist claiming to be foo 1.0, when used to build a wheel, should produce a wheel that’s functionally equivalent to any other foo 1.0 wheel”). Some of these are obvious (like that one), others are not (for example “if you build a sdist from a sdist, you should get back an equivalent sdist”).