Full-size is objectively superior, everything else is a mitigation for sub-optimal circumstances.
If you have reduced desk space and need to conserve your keyboard size to allow more room for a mouse then absolutely, pick as small a keyboard as you’re comfortable with to get sufficient mousing space.
Anything beyond that is subjective personal preference, which again I have no qualms with, but calling it better without further qualification is going to invite incredulity.
My biggest problem with that “monstrosity” is that it’s ortholinear.
You imply that such a thing being “optimal” is absurd, but if you had infinite usable desk space then what, exactly, would be the argument against it? If space is not a consideration then what does it matter if you don’t use every key?
Lots of people like smaller keyboards, and that’s perfectly fine. I get it as an aesthetic choice, and for many people it may not impact their daily use at all. But you will not convince me that removing the option of having additional keys for binding is a non-zero cost, even if they’re not currently being used.
For what it’s worth, I never used anything like that monstrosity, but I was quite happy with my G15 for the time that I had it which had 18 additional keys, plus media control, over a typical full size.