Crawley BJP Jan6 1961 explained how high pH together with reduced concentration of the developing agent affected acutance in the case of metol."When the concentration of developing agency is lowered in this way...the non-availability of considerable supplies of fresh developer has some prevent the image spread due to the infection of adjacent crystals."
IDK if this happens with p-aminophenol,it raises the question if post 1964 Rodinal is sharper than the previous version.