It seems to be accepted that questions about Japanese dialects are on-topic here and questions about other languages are off-topic. But let's look at the grey areas:
- Questions about Kansi, Hiroshima, Yamagata dialects seem to be OK.
- Okinawan and the other Ryukyuan languages seem to be regarded as languages by linguists but as dialects of Japanese by the Japanese government. (Though I can't find official confirmation of this so far.)
- Linguists do not regard Ainu to be related to Japanese at all, let alone a dialect. I had believed the Japanese government didn't count it as a Japanese dialect either, but I haven't be able to confirmation either way.)
- Then there is Hachijo, which is not Ryukyuan, but also not mutually intelligible with standard Japanese.
- And then there is Kagoshima-ben, which is mutually intelligible to some degree but apparently regarded as the most difficult / most divergent Japanese dialect.
Where should we draw the line, out of the following options?
- All language varieties native to Japan are OK? (So obviously not immigrant languages like Chinese and Korean)
- All Japonic languages are OK? (so no Ainu either)
- Ryukyuan languages are also separate but Hachijo is Japanese.
- Only the varieties on the main islands are OK.
- Even Kagoshima ben isn't really Japanese.
(Or any other option.)