The primary benefit here is automation and ease of management, especially for CI or AI agent workflows, rather than saving tiny amounts of time on VM setup. Docker's role is to offer a consistent and familiar management interface, which can be useful for automation and scaling, not for shaving milliseconds off VM boot times
What I think you’re not addressing is the question about the Linux VM that Docker requires on a Mac. I don’t think there is a question about the benefits of Docker from a management point of view. The question is — is it worth keeping around a running Linux VM just to get those management benefits. Since you’re not actually using Docker (the daemon) to run Macs in a container, how much of that micro Linux VM is necessary? Is that overhead worth it?
(This is coming from someone who keeps colima running all the time on my Mac)