If RR based verification really is a MUST, shouldn't that be written down somewhere (more authoritative than the multi6 mailing list), along with at least a basic explanation of why?
Can anyone provide a pointer to such a requirement, preferably in an archival document that is at least BCP (and preferably standards-track)?
FWIW, the biggest impediment for moving past "the IESG must review and approve all specifications" is the view that working groups don't understand requirements like this one. Having WG participants "guess why" isn't likely to help improve understanding.
As IESG is ignorant on producing such a document, don't expect me to overrule it.