The "Popularity among users" contradicts the "Popularity among creators". There are many reasons that the number of created works is a better ranking of popularity than search frequency. The amount of created works is DEFINITE. We know how many there are and how many people made them. Making things is hard; the numbers can't be jacked by a vocal minority.
A naive reading of the rankings might lead you to believe there is a disconnect between the people consuming R18 doujins and the people making them. This is understandable, because there are many examples where this sort of thing happened, for example AAA video games. But remember hentai and independently published doujins are made by the very demographic that is the most obsessed with them. Perverted Japanese dudes.
On top of being a unique market where the makers and buyers are the same demographic, and makers are often doing things out of passion because they are the only ones who will ever make the fucked up smut they are dreaming of, DLsite is a STOREFRONT where people are BUYING and SELLING things for MONEY. It is affected by market trends. It is fucking insane to think that NTR was been the most popular thing for years at this point, but still at no point in the last several years of public data in a competitive market has that led to an increase in people creating and making money from NTR comics. These rankings come out every month and I have yet to find one where NTR isn't the most searched or one where NTR even appears in the "Popular among creators" section. If NTR was this fucking popular there would be more people making money off of it. There's no explanation for this behavior other than a small handful of porn addicts who are constantly looking for more cuck porn. The stats are released here if you want to look through all of them yourself:
https://ci-en.net/creator/13680/article 