It appears that git format-patch + git send-email is a mature and widely used approach. Wouldn’t it make more sense for the open source community to work on streamlining that process instead of trying to build momentum with new approaches?

For what it's worth, under the hood tangled is extremely similar to this approach.

Personally as just a random person in the community I've been building an appview for tangled that lets you interact with it as if you were just using git format-patch + git send-email + some MUA.

You can conceptually treat the tangled lexicon as a schema for encoding a git patchset based mailing list into IPLD/atproto records and vice versa. Doing this is slightly lossy but only barely. Otherwise it's pretty seamless.