Counter point: I adopted it internally at Google (there's a backend for Piper, Google's monorepo Perforce thingy). I don't do my day-to-day work in the monorepo but I still jump in there once or twice a week. I adopted JJ because the existing frontend (Mercurial-based) is slow while JJ is fast.

It's nice, I really like it! I'll probably switch to it as my main VCS eventually. But it doesn't feel that important to me. Even though my main work involves quite a lot of annoying rebases which is where JJ really seems to shine.

I dunno I guess it's just that a) I've really mastered git and have a deeply-rooted workflow in it and b) despite my project involving annoying rebases, version control still isn't very high on the list of problems I have.

So yeah I'm basically bullish on JJ as a technology but I think movement from Git is inevitably gonna be slow and steady.