Sorry, friend, but Bubble doesn’t provide clear direction on anything related to the forum/community (they never really have)… we just kind of figure it out for ourselves.
The idea category in the forum existed long before the ideaboard, so folks are used to posting their ideas in that category. Then, the ideaboard came along, and I’m sure Bubble would rather have folks submitting their ideas to the board. However, like you, most folks have noticed the ideaboard isn’t very active, so people seem to be gravitating to submitting an idea to the board and posting a link to the idea in a new topic in the idea category here in the forum. I’m sure that isn’t what Bubble had in mind, but people are doing what they think gives them the best chance of making their ideas visible so other people will upvote them, and you can’t blame them for doing that because, to your point, Bubble hasn’t provided any direction.
With regard to a feature request being “accepted,” well, that’s not really a thing. You submit your idea to the ideaboard, the forum, or both, and that’s that. It either gets implemented by Bubble or it doesn’t, and the latter is more likely because that’s just reality.
Anyway, this reply probably isn’t what you wanted, but I thought some context might help (or at the very least couldn’t hurt).
Best…
Mike
Edit: look at Bubble providing direction in this thread now… a new day is dawning!