Software isn't as faultless as you suggest. The default alarm app on my phone occasionally fails to go off (not an issue with Silent Mode or DND).
> The only people busy enough to warrant an actual human doing that stuff are executives.
Life is short. It is absolutely worthwhile to spend as little time doing trivial work if possible, and avoid decision fatigue on unimportant decisions. We are nowhere close to the usefulness of a secretary in our devices.