Scaling up/down is usually for CPU-bound jobs. EC2 has a bad cost/CPU workload ratio when compared to a provider like Linode. You really have to bank on the hourly billing (as the article touched on) to make the cost it worthwhile.

I would imagine for a lot of people, they don't need that type of granularity when spinning up and shutting down a server instance. Unless you have some automation to spin up new instances as load increases for short bursts, I could see people working on a schedule that is across a few days.