I mean, Satanic Panuc and the economy were big factors, but I really fo suspect thet it seems Mentzer was not well received, which surprises me as someone who wasn't there, because I have only ever heard praise for BECMI and the changes.
Since the dominant marketing de facto was learning from an older brother or cousin, I wonder if the nation's older brothers and cousins sinply refused the changeover and just Xeroxed B/X for the next gen or something...?
Also, I can't help but wonder if they stopped tracking which version sold because Moldvay kept outselling Mentzer and that was embarrassing
My recollection is that Mentzer was very well received. It dropped off, certainly, but that dropoff was in '84, when the bottom apparently fell out of the market. It did gangbusters the first year, and was also the big face of D&D for most of the international market.
The red box Elmore cover art remains iconic 35+ years later, and was re-used for a 4E starter set because it's so well known. I think they stopped tracking them separately simply because the '83 Basic and Expert were replacements for the '81 Basic & Expert, and so they stopped producing the older ones.
Well, the Starter Set has a Module, not a solo play example? I'm not sufficiently familiar with the differences, I was always under the impression that they were minor?
The '81 Basic came with Keep on the Borderlands. '83 Basic has first a solo Choose Your Own Adventure style tutorial in the Players' Guide, followed by a small solo tutorial adventure with eight or ten chambers of dungeon, mapping and more full rules. It also has a bigger sample dungeon (Castle Mistamere) than the Haunted Keep in Moldvay, though not a full module. It's a pretty decent one-level dungeon for a new DM to run, with some outdoor elements, though, and also provides a map for and brief overview of a second level to the dungeon, with suggestions to the DM about how to fill it out and properly stock it.
Mechanics-wise the two versions are VERY similar, though there are small differences in the actual rules and substantial ones in presentation. Mentzer Basic splits the book into two volumes, one for players and one for DMs, adds the tutorial to the player book, and generally more spacious layout and more art, gorgeous Elmore pieces throughout, for a more consistent, professional-looking aesthetic. The DM book goes into more detail and gives more advice.
The '84 drop-off is because big box stores stopped carrying D&D. They didn't reorder and sold out of their existing stock. The economy was rough, so there was less disposable income. I think the edition changes confused retailers more than players. Do they stock AD&D books? Or the much more boardgame-friendly box sets? The Satanic Panic was just social pressure to not learn about D&D. Worked on some, worked about as well as D.A.R.E. on others.
I think there was some confusion, but as far as I recall, only Sears and Penney's stopped carrying them in '84. They were still routinely available in big box Toys R Us stores, smaller Kay-Bee Toys in malls, and in B. Dalton's and Waldenbooks for several more years. Book stores, in particular had extra promotional materials for 2nd Ed AD&D five years later.
All the evidence points to market saturation. Growth was so strong that by 84 pretty much anyone that wanted D&D had D&D. It was a niche hobby with a limited appeal.
I agree that market saturation and the end of the fad are more likely the main factors. D&D did well in the 70s, but didn't explode onto the mass market until late '79 thanks to the Egbert case. It had three more years of serious boom times, but then it fell off.
