> can the admin of a node choose which tags he supports
This is the default behavior now; I worry about people misusing the tags feature or doing tag spam. Unsupported tags from remote boards are rewritten to "random" but I could also add features to filter out specific tags (eg NSFW).
> Allowing each admin to create their own tags seems like a reasonable compromise between full on user board/tag creation and predefined tags.
Bingo.
> Wait one second, decentralized textboard? Isn't that just an anonymous Usenet knockoff?
In a sense, yeah. But who really likes Google Groups? NNTPchan is definitely an inspiration in some ways, but I don't agree with all the design decisions.
If you have any thoughts like "I'd like to see..." or "I don't want to see..." that would be super useful!