I'll stick to DIY analogies, since it appears to speak to us.

In this case the author is using a tool for operating on lists on a thing that's not a list.

It's like they're trying to use a track / plunge saw for cross-cutting a single 2x4. You can do it, but you'll need to rig up some scaffolding (a list) around it in order for the track to have something to balance on. Meanwhile there's a circular saw and a speed square next to you on the table.