It's a big fancy nice feature, but you sometimes know ahead of time whether a diff is small enough not to bother with abridging. Also, maybe thresh can be a good enough local-first code review system with some kind of remote syncing (#6) that people will want to use it who don't want any of the AI stuff ever. I kinda doubt that, but who knows.
In either case, I think we should allow turning it on/off, defaulting to on, at invocation time through a CLI flag and globally through the config file. We should support e.g. leaving it on all the time and turning it off here and there and leaving it off all the time and turning it on here and there.