I think that one of the reasons is that the mailing list workflow tends to produce a final deliverable (commit) that makes sense by itself because the whole con

I think that one of the reasons is that the mailing list workflow tends to produce a final deliverable (commit) that makes sense by itself because the whole context will be hard to find (no direct link to mailing list discussion). On GitHub instead when you find a commit you’re always one click away from the PR that produced it, with its discussion inside.