You can turn a local model on and off as needed, and it will still function as expected. If you turn off your self-hosted server, you don't get email.

With self-hosted email, you need persistent infrastructure and domain knowledge to leverage it. With a local model, you just click a button and tell it what to do.

With email, there is a necessary burden to outsource. Your local model is just there like Chrome/Edge/Safari is just there, there is no burden.