Whether it's you misinterpreting them, or them being put badly makes no difference. The fact is that there has never been an issue with apps creating free accounts on services
Again, it sounds like you're just assuming "Oh, they could never do something that stupid, of course that's allowed." When it looks like that's exactly why apple is rejecting apps. The external authentication/creating accounts. And that is why everyone is saying what apple is doing is stupid and going too far.
I'll give you another quote from the dropbox forums.
My app update just got rejected with the old sdk that doesn't have a link to the desktop stuff. It never leaves the app and there is no option to buy anything. They said providing account registration for accounts that may carry a subscription is not appropriate.
Apple is rejecting apps for allowing people to create a free account that may be updated later. Simple as that. And I think the reason you deny that so fiercely is because you realize how stupid that is