That rule applies to the local thread section and I believe it was put in place to prevent users from creating multiple local threads in that section as it could get it clogged up and make it difficult for users to find a thread that applies to their language.
If a local board exists then anyone can actually create a thread there and join discussions.

Some languages actually do have multiple threads in the local thread section, but the users who created them are not banned, Maybe cause those threads are specific and do not contribute to spam.