I am from Russia (not in local lw.ru). I have read HPMoR at age 12 and it immediately became my favourite book and holds it’s place even now. I find Eliezer Yudkowsky’s views on most things the most convincing of all the other I saw.
More detailed version organized as Shortform comments thread: https://www.lesswrong.com/posts/zbSsSwEfdEuaqCRmz/eniscien-s-shortform?commentId=JtpxcmxMt2ycd4K5s
It is certainly not just plaincrash, there is at least also The Erogamer.
If I needed to guess why, I would say that it is not about studying metaphysics per se, but about what people will be ready to give a try for reasoning about realityfluid metaphysics—same kind of people who will give a try writing about it inside of online erotica. Though I am actually even less sure why you can’t publish about realityfluid metaphysics in journals.