Why is metafiction so rare in fiction?

I've noticed that true metafiction seems surprisingly rare. Works like Umineko, House of Leaves, and If on a Winter's Night a Traveler are some of the best-known examples, but it's hard to find others that really explore metafiction in a major way.

Why do you think this type of story is so uncommon? Is it because it's difficult to write, has a niche audience, or something else?

Also, if you know any other great metafictional novels, visual novels, manga, games, or films, I'd love to hear your recommendations.