This sentence looks a bit different from the previous ones. Was it also discussed that this should go?

(Although... we do not seem to have any test for it anyway, so we may just well remove it...)

It reads like another case of precedence over what might have been expressed in a browser-friendly package document -- don't use the layout behaviours that were defined for a browser rendering.

You can add properties to the package metadata if you want to control layout and rendering, or create custom attributes in xhtml, so explicitly banning from linked resources when we no longer expect the bff format seems a bit paranoid. No one's going to go through the effort of defining instructions through linked records when the simpler methods exist.