I know from personal experience that a lot of fans of Western RPGs consider Japanese RPGs trash. And even that there fans of Western games who consider Japanese games in general bad.
For instance, people on the Escapist, at least the years ago I went before abandoning the site, were very Western centric in their tastes. I don't know if that's changed. But for instance, most people there didn't like most Japanese games.
It was a bit of a "culture shock" of sorts, if you can call it that. Because for me, gaming has always been synonymous with Nintendo, SEGA, Sony, Namco, Square, Atlus, Nippon Ichi, Sunsoft, SNK, and ect.
There's also several companies and organizations that I think hold those same biases. Just as I'm biased in favor of Japanese games, and outside of Japanese games, have very "Japanese tastes", for games like Undertale, or Korean games.
A lot of Japanese games simply weren't accepted on Steam before Recettear helped open the floodgates. And Cave shooters like Mushihimesama and DoDonPachi probably weren't accepted on GoG because they were seen as very Japanese, and very niche.
Basically "not good enough" for the platform.
I always supported Greenlight from the beginning. Because even though I knew it would let a lot of bad games selling only on meme references or the like get in. It was also what was taking down the barrier from Japanese games, and especially niche Japanese games and niche indie games of all varieties from getting on Steam. I would rather there be bad games on Steam, then me not be able to buy the games I would like.