how can acid harm bacteria when said acid
(a) is only added in very miniscule amount?
(b) is there to shift the pH into a zone which bacteria like?
(c) said acid already engaged into a chemical reaction (with chalk, alkalines etc) and thus, is no more there... and it took some of the alkalines with it...
yes the increased surface area is a huge factor.
the water solubility is derived also by other factors. For example, I have MagnesiaChalk here which 60% Ca 30% Mg came as pellets for fields. Ground that to fine powder - but still, nowhere near water soluble. As good as no EC, slowly rises but still after 30 mins not finished.
On the other hand, Epsom Salt water soluble after few seconds....
btw plants can also actively break out minerals from the soil by releasing substances.