As of recently, librsvg-2.36.1 wants to pull in dev-libs/gobject-introspection despite a global "-introspection". If this is a requirement by the package, I think it should be fixed before entering portage.
The only thing pulled in this regard with -introspection is dev-libs/gobject-introspection-common, and that's pretty much the same case as gtk-doc-am - eautoreconf requirement. So, basically INVALID.
Exactly