I love how Ben is paying attention to the debate about the numbers he’s releasing and responding with great insight. How do sales of AD&D Player’s Handbooks (PHBs) and Dungeon Master’s Guides (DMGs) translate to monster products? Seems like that answer is of more than historical interest, since...
That's true, but the year-to-year numbers as new DMGs and new PHBs are being sold from 1979 until the fall off between 83 and 84 the MM is always below the two of them. You have folks getting the PHB, fewer folks getting the DMG, and then not all of those folks also picking up the MM.
That pattern repeats with the 2e Monstrous Compendium, though the weird product design of the MC does make it a bit hard to compare. But far fewer lifetime copies of the MC1 were sold than the 2e DMG. And the 2e DMG + Revised 2e DMG has more sales than the MC1 + Monstrous Manual. I suppose folks could just be buying any old MC (total sales of MC1-MC4 is higher than the DMG sales, but you have to assume that many people bought all 4 of them).
I can imagine running games with just the 1e DMG because there are at least tables of monster stats in it. But 2e cut all that out and assumed you'd be buying a monster book, so it's odd. I do wonder if many of the PHB and DMG sales just were going to people with the Basic and Expert sets who were using the monsters out of there?