Once upon a time I was heavily involved with the Textpattern community, but I haven’t used or kept track of TXP for several years now. It randomly popped into my head over lunch that Textpattern originally had an ethos which aligned really well with IndieWeb ideals.
It had a plugin system for extending the core, could define custom metadata, override how to display particular articles, and it was also easy to modify themes to add things like microformats/special meta tages, etc. Looking back, it sounds ideal for some users?
I could only find a passing mention in the IndieWeb wiki. If I find the time, I might explore and document setting up an IndieWeb-integrated site using Textpattern.