I agree with most of this but the point about QA gating deploys should be amended. A 5 minute integration test on a pre-flight box in the production environment

I agree with most of this but the point about QA gating deploys should be amended. A 5 minute integration test on a pre-flight box in the production environment by the deploying engineer is a form of QA, and can catch a lot of issues. It shouldn’t be considered anti pattern. Manually verifying critical paths in production before putting them live is about the best thing you can do to ensure no push results in catastrophic breakage. Without such a preflight box, or automated incremental rollouts, you are kind of doing a Hail Mary, since you are exposing all users immediately to a system that has not been verified in production before going live.