I don’t know if I agree with you. If an ADSB out can be installed in any type certified aircraft without a 337 why do the manufacturers bother with a STC? I’ve installed a Stratus transponder in a Pawnee using the policy you quoted. I didn’t consider it an informational 337 when I did it. The FAA gets information on which airplanes have ADSB when they’re flown in the national airspace system.

Experimental aircraft are a whole different subject.