For systems of sufficient scale, it's fairly standard to keep flag changes outside of git so that they can be flipped without a pr. That way the flag change UI can apply other validation steps before any change is attempted such as ensuring valid enrolment ranges (no accidental overlap, and no accidental rollouts to 100% instead of 10%), and the associated rollout analytics can be shown alongside the changes.

You can also override things in emergencies more easily, which is the parent's point.