The people who are "managers" are also splitting their time. They only need to spend maybe 20% of their time in actual supervisory work. The rest of their time is spent on tasks that are delegated to them by their higher-ups. These tasks are largely forms of information processing: Gathering, analyzing, and communicating. Excel and PowerPoint. But they are typically one-time tasks that are not worth automating.

I was happy with the 20% supervision, no problem. But the 80% information processing tasks just weren't interesting to me.

When they finally posted an opening for my old job, I went to the boss and asked: "What do you want me to be, a mediocre manager or a great engineer?" Oddly enough, moving me back to engineering resulted in a second promotion on top of the first. Meanwhile, I did enjoy receiving a fair amount of management training and insider understanding about how the business works.