A more interesting comparison may be to DK-50, which was considered not to be a fine grain developer, but to produce moderately fine grain in its era:
Metol 2.5 g
Sodium sulfite (anh) 30 g
Hydroquinone 2.5 g
Sodium metaborate 10 g
Potassium bromide 500 mg
WTM 1 l
DK-50 has about half the metol and bromide and about twice the metaborate and sulfite (very roughly).
The sulfite in the BJ formula is not sufficient to exercise very much solvent effect, so the fine grain must come from the metol and bromide acting together.
It's perhaps worth looking at the Dilute DK-50 formula that was in use in the early 1960's as this is closer to the formula here. Geoffrey Crawley puublished it in his series of artcles 1960/61 on Developers in the BJP it was in subsequent Anuals for many years in the Fornulae section.
DK-50 is one of Kodak's variations/evolutions of the earlier Wellington & Ward Buffered Borax formula, lurking somewhere in an obscure publication there's probably a Borax version D-50. Kodak tried and published a few Sodium Metaborate (Kodalk) buffered versions of common formulae including DK76 and DK76b.