Wow; I just re-read the old socialcg minutes for why we don't have an extension process, and apparently I just got tired of working on it without a vote and downvoted it out of consensus.

https://chat.indieweb.org/social/2018-09-12

It was a perfectly reasonable proposal.

https://github.com/w3c/activitystreams/wiki/Extension-process/fa6b7c289da5beac15273ffc7a015ca15c97b489

I should have stuck to it! #ActivityPub would be much better now with that process in place!