For the record, I don't have a horse in this race, so I don't care about the outcome either way. Also, I have been blending multiple files as a noise-reduction technique for nearly a decade (starting with my P30+, in fact) and very much endorse its use when the circumstances allow.
That said, though, none of the test results discussed at the link you cited are apples-to-apples relevant to the proposed test, which is to compare frame-averaged photos taken at ISO 50 and 1600 with the exposure length adjusted as appropriate, not to compare a single-frame photo taken at ISO 50 to a frame-averaged photo taken at ISO 1600.
Because whatever image quality improvements are achieved via frame-averaging will surely apply to both photos and there is no way I can think of that a photo taken at ISO 1600 can close the IQ gap to a similar photo taken at ISO 50, hence my comment (and your gut response noted in your subsequent comments.)
Again, I'm not trying to poop in front of this parade, because I think this is a wonderful tool to have available, only to point out that it's not the magic bullet / universal solution for every photographic situation that some photographers want it to be...