Never said you said EQ was dumb either lol, so please don't be so sensitive. I made that comment about those Ph.D. can't be that dumb simply trying to say that might have designed their systems to EQ above the Schreider freqeuncey based on something they know, that might not have been considered by those who disagreed with the approach. As far as whether a good speaker in a properly configured room will likely sound better without EQ, that seems like a general statement with qualifiers so sounds fair.. I would like to add that your "the science behind the Schroeder frequency can’t be disputed" comment may well be 100% true. Whether to apply REQ to frequencies above that point could still be debatable, as it may depend on many other factors. By the way, unless you are in a very small room, if you set your limit to 300 Hz, that could be well above the transition frequency for your room already, just for argument sake and I know you know that already..
Just for further clarity, Anthem ARC's "option" to EQ full range is applicable to the AVM and D series. Below is from Audioholics.com interview with their Dr. Peter Schuck and Nick Platsis.
https://www.audioholics.com/room-acoustics/anthem-arc-room-eq-interview
So part of reason, aside from that related to Schroeder's findings, why they limit the non AVM/D series to 5 kHz could be hardware/cost related.
Understood, preference is also a subjective thing, so it is great that MultEQ bass and DEQ off works well for you. As we both know, many prefer to have Audyssey "off" completely while others would prefer everything "on", and full range.
Anyway, sorry if I got you side tracked from your original question per your thread title, and thank you for sharing Audyssey's response confirming DEQ applies regardless of the transition frequency setting. That actual makes sense to me.