Much of the progress of civilization has involved tools that turn things from skills which require focus into things that are automated. It frees the mind to focus on other, more important things.
I could also just have an "on" button I have to hold, count seconds in my head, and stop when I think it's done, but thankfully no one is advocating for regressing UI quite that much....yet.
It's a skill like any other, which of course has vanished, much like reading maps and math in head.