Edit: Anyway, the culture of celebrating authors in general rather than trying to create franchises helps a lot for all sorts of books.
Geographical distinctions don't really make sense in deciding preference, you start with genre elements and pick from there, regardless if it's Western or Japanese. Ignoring a work because it comes from X country would just be bizarre. As a sci-fi or fantasy fan I don't make distinctions between Japanese or Korean or Western works, nor do I see other fans doing so. For example, I wouldn't be comparing Satoshi Hase's Beatless in the context of "Japanese" works, I'd be comparing it to other AI works. The only limiting factor is translation.
But cross-genre pollination doesn't really happen nowadays, most shounen readers will never go or even avoid mecha, and so forth. Otaku culture especially is much more fragmented today than in the early 2010s.
You realize Umeniko got an anime? Yes, some of the people who watched that anime probably went to read the books, is that really so hard to believe? Authors who got their works animated see a lot more book sales as well. Then as they read those books they might want more so they look for adjacent books, fueling the entire industry.
Contemporary Literary Fiction as in the article is separated by far more cultural layers, there is virtually no cross pollination with the otaku subculture. You are far more likely to get someone who reads Westen literature to expand to Japanese works than an otaku to do so.