That's just nonsense.The syllogism is exactly as I said it:
Slow is good
Slower is better
Therefore, slowest is best.
And what is the slowest possible publication speed? Zero. Stopping.
The truth is that customers have different amounts of money and attention to devote to D&D books. If you're releasing things at a really slow pace, you're probably going to see most potential customers buying everything produced. If you release a few more books, people will be pickier with what they buy, but you might still get most of them to buy most books. And if you release a lot of books, people are going to start becoming real picky. Somewhere along this scale you'll find a pace that maximizes your profit, and that's where a good capitalist would want to be.