I don't see the problem. For example, BBS is the most popular forum software in the west, it doesn't mean that make everyone's the same in every forum, the cultures vary wildly, even if there are certain cultural traits that are inevitable outcomes of the BBS structure.
Imageboards have a much smaller following in the west so there's less variety but I don't think it's actually the same people using all of them, it's just the unique voice and culture that develops out of the format.
And there are textboards, there are imageboards, and now there are real-time imageboards, which I think present a very interesting development, though they're exclusively focused on /a/ at the moment. https://github.com/bakape/meguca
I feel like they have the potential to take over static imageboards in popularity outside 4ch/8ch in the near-future, especially because they have little trouble with "going dead" or maintaining momentum, which plagues every alternative text/imageboard. You just need ~5 active posters for the board to feel alive and well, as the posters rise, it scales by splitting the discussion into separate threads.
A bit of a gimmick, but there's also two different sshchan's being developed over at lainchan:
They're teletext inspired textboards that run purely through terminal
Try them out: