The “culture” around learning Japanese is so different from other languages. There’s a large amount of software engineers studying the language, so there’s tons of apps/websites that center around it (for better or worse).

The communities are also… particular. People tend to espouse certain deep beliefs or attitudes that you just don’t see for other languages (and I don’t think complexity is the reason; you don’t see that for Chinese or Russian or Finnish, to name some other notoriously hard languages).

Funny thing is, these communities aren’t readily visible in real life. At the Japanese language school I attend people are mostly regular people with regular lives and regular limitations. Online, you’d believe that everybody did Wanikani on Adderall for several hours a day.

There's no real reason to learn Finnish other than curiosity, so I'm not surprised there's no community around learning it. You can move to Finland without knowing the language at all, since everyone else around you will happily speak English with you. Hell, you can even get Finnish citizenship as long as you learn Swedish instead. And when a language is spoken by around five million people, there's no large amount of creative works only unlocked by learning the language either.

(I'm a native Finnish speaker)