kek I mean it makes a lot of sense that you found endless amounts of yaoi* instead of whatever you were looking for, since Stardust Crusaders had only like 4 female characters.
*yaoi: male x male art and (fan)fiction made by women for a female audience. Its rough Western equivalent is called "slash" (after "male/male"). It's different from bara, which is gay porn drawn by and for gay men.>>13588
Yaoi/BL* has been popular since the 70s, I think. And JoJo has always had a significant amount of female fans, most (but not all) of which are "fujoshi"†. Jotakak, the pairing of Jotaro and Kakyoin, is extremely popular, probably the most popular JoJo ship‡, because Stardust Crusaders itself is the most popular JoJo part of all time. This has been true since the late 80s which is when Part 3 started. JoJo attracts so many female fans because of its huge cast of diverse, cool male characters dressed in flamboyant and stylish clothes, and fujoshi in particular because said male characters, who are usually if not always single, spend a lot of time together and often have passionate feelings for each other in the form of rivalries, friendships, etc., which makes it easy for fujoshi to interpret their relationships as romantic and/or sexual in fan-created media (which shippers‡ in general do whenever there's tension between two characters).
As for the materialist explanation for the popularity of yaoi and the existence of fujoshi, there are already a couple of threads where they have been discussed (in short: there are many different reasons, some of which haven't been talked about on this board). Also, female creators, many of which were yaoi artists, used to be the majority at Comiket (and still are in a number of other Japanese anime/manga conventions) until lolicon artists started to actively compete against them with more sexually explicit content (see: https://crawfordpro.wordpress.com/2020/05/03/article-the-castle-of-doom-and-the-lolicon-boom/
). So, if anything, yaoi was already popular before straight hentai doujinshi (through lolicon, I presume) experienced its own "boom", though I'm not sure of how popular straight hentai made by men was before that. However, this last part is just speculation based on what I've learned so far.
*BL: "boy's love", an alternative term for yaoi, and more commonly used nowadays.
†fujoshi: women and girls who obsess over yaoi and usually enjoy "shipping"‡ male characters from non-BL media as a hobby. Men who enjoy BL are called "fudanshi".
‡shipping: supporting the idea of two fictional characters, regardless of their sex, being together in a romantic/sexual relationship. The couples themselves are called "ships", while their fans are called "shippers". Usually in reference to couples that haven't been confirmed or deconfirmed in canon yet, or will definitely never happen in canon.