So you're saying that Crawley and the chemists at Agfa, Kodak & Ilford etc don't know what they are doing when they put such small quantities of Metabisulphite etc in a developer

Paterson/Crawley put less in one of their other developers, sometimes small quantities have disproportionally beneficial effects.

Acutol-S / FX-15 isn't a normal fine grain film developer, it was formulated specifically to give high acutance which it gives at the expense of a slight increase in grain and loss of tonality. It's no co-incidence that the other developers using these small quantities all give additional acutance.

Take the Metabisulphite & the Carbonate out and you'll have a developer with quite different attributes.

Ian