Milpool appears to be a mole sneaking into the Zone world in order to blow it up. Take away minus and plus development, and it simply ain't any kind of Zone System anymore. But that brings up the dilemma in what a "zone" even means.
A) To some, you've always got a dynamic model of textural value assigned between Zones 2 and 7, so in effect have to stretch the space occupied by each intervening segment if the scene contrast range exceeds 7 stops (or 9 stops if you include pure black and pure white).
B) To others, each Zone represents one distinct stop of exposure value. Therefore, if the scene contrast range has 12 stops, you need to think of 12 zones to accommodate it; and if a low contrast scene of, say, only 4 stops, you've only got four zones to contend with.
Therefore, those little gray scale Zone stickers people put around spot meter dials are inherently misleading with respect to how films differ in relation to one another and how scene contrast can also widely differ. So should those little gray scales be elastic like a rubber band (scenario A) or rigid with potentially differing quantities of centipede segments (scenario B) ?
Now I've complicated things even more, but actually not me at all, because there are in fact so many competing, even contradictory,
variations of the Zone System. That doesn't bother me at all because I tend to visualize actual specific film curves when out shooting, rather than what species of segmented centipede is involved. And yes, one of the most useful tools is how those curves can be tweaked by thoughtful development variations, despite what Milpool claims.
But I've spent a lot of time doing densitometer plots, so realize my own manner of visualization might not be practical for others. Tools are just that - tools. Good tools make life in the darkroom a lot easier. But no tool is more important than your own eyes.