It has all sorts of gamification that gets in the way, it’s easy to over-silo discussions, it has a concept of “answered” that’s not really appropriate for a lot of project level discussion, it has all sorts of other extraneous crap like “reactions,” and—most importantly—it’s fundamentally implemented as a web page that everyone involved needs visit regularly to see when there’s something new and to respond to that.

Discourse would be fine if it were a front end to a mailing list and didn’t have the excess categorization and gamification crap. Instead it’s a web forum with a mailing list mode tacked on by people who never did substantial technical work using mailing lists.