[Arnt]

FWIW the same approach was proposed in the nineties. IIRC the main argument against was that the argument to support it is even worse than for v6. The first few sites to get non-4 addresses aren't reachable by anyone, and have to ask everyone to extend their stack and listen to an endless series of answers along the lines of "our existing stack has IP routing to everyone else, why don't you deal with your problem instead of bothering us".

I guess it's an RFC 1925 reference. Truth 6: If you can make a few specific people responsible for making everyone migrate/extend, life's simpler for everyone (else). And truth 11: 30 years later, the same proposal but garnished with JWT.