Yeah, CD is a big game changer here. Managing config separately from code is a big pain (as that piece points out in colorful detail), and as the countervailing painfulness of a deploy drops toward zero, it becomes better and better to just hardcode some consts. "Business rules" just become "code you write". Easier to change, test, and reason about. At my last job we moved to CD and it was fun to see everyone (haltingly, sometimes unwillingly) change their approach to this.

There's still a place for configs and even DSLs (multiple deployments, on-prem software, biz logic written by non-programmers, etc) but CD eliminates the huge class of "this is too expensive to deploy changes to" cases.