Those "vague suggestions" actually seem to include some pretty specific examples.
> A user’s entire "home" directory. Individual files and directories inside the home directory should still be allowed, but user agents should not generally let users give blanket access to the entire directory.
I think the point is that as long as the user is sharing things on purpose and not by accident, it should be allowed. Selecting the root of the home directory would probably share a lot of things the user didn't really intend to share (because a lot of apps just dump random config files and stuff in there), but if they specifically select a subfolder they probably have a good idea of what that folder contains.