I probably over-reacted to the "consensus" claim, though still feel it is a bit over-the-top. Yes, a composite does have some advantages over luan backing.
I get that Adzel is a composite rather than a laminate, so no luan backing. It's scarcely the only brand of composite, though, and other manufacturers use other brands. There are also laminates that use synthetic backing rather than luan. Plus, much of the advertising claims by Gulfstream & Coachmen are versus the old stick & tin construction, not filon-luan laminate.
I'll grant that a luan-backed laminate can be damaged by water intrusion, but water intrusion is a serious problem no matter what exterior sidewall material is in use. Floors still rot, mold still forms, interior walls still deteriorate, etc. And the composite skin is still bonded to the frame and can still detach (delaminate) if mositure damages the adhesive. So, you still need to stay on the lookout for leaks at seams and windows, and using something like Adzel is not a panacea. It's probably better than what those companies were using before, though.