Spoken like a true arm chair renovator Jim.
The old blocking debate. Jim how many structural engineers have you worked with in the past seven years. Yourself - on site?
I'd be talking to them before you start saying that blocking does nothing for deflection in a room.
I'll ask again where it states that no construction adhesive is to be used under the plywood. It certainly doesn't state that in the Ditra manual you posted a link to. Blocking can do wonders for stiffing up a floor - if done right and if over the proper spans. A structural engineer can advise you on this much better than a retired Defense Engineer - I would think. I've never ran into a defense engineer on site but I do work with framers and structural engineers all the time.
I bet your buddy CX told you that one Jim - No?