Again from what the folks I know can remember through the fog....
of Northwoods it was cartridge heaters and even though they are inexpensive it did ruin them at times.Another opinion shared with me from someone who I absolutely respect this method was described as a "solution searching for a problem..."
Or, in other words blushing commonly happens with steam or conventional neck removal and just as commonly we fix it and make it go away. No biggie, it's been done this way for half a century or more.
It's also possible at times, not always to remove a neck with minimal if no blushing at all. It just depends on how much glue someone back in time poured into the dovetail.... and/or slathered it on the cheeks.....
In the business some vintages of certain brands are known to be more resettable than others in terms of being problematic or not. In addition some vintages of lacquer for some brands are also know to be more forgiving or totally suck making it impossible to get a neck off without having to do a goodly amount of finish touch-up. Even the heel design of certain brands (Guild) can dictate how much time you are going to be spending fixing mistakes.....
Luthiers with this level of experience, and Dave Collins has this experience know which ones will cooperate and which ones to kick the can down the road if possible or employ the ole "punitive quotation" to persuade someone to go elsewhere.
My impression is that the dry heat method does not guarantee that you won't have finish touch-up to do. Stuff happens, and again taking into account what I shared about some eras of instruments from some makers being a nightmare to reset it's likely that this method will not guarantee that any reset will be without the need for finish touch-up or the heel will break in half, etc.
You know too these things that some folks develop a block of sorts to thinking that it will suck for them are not always anything to be afraid of. Fretting the guitar on a newly built and finished guitar with the neck on the instrument is one that many here have expressed real fear of doing. Touching up the finish after a neck reset is not hard, takes little time beyond waiting for the finish to cure and if learned properly from someone who knows what they are doing it's nothing to be fearful of.
This lends some Creedence to the idea that this is a solution searching for a problem. Besides the steam pot and probe is great to raise the RH in your shop in a Michigan winter.