I am instinctively against over-simplification of this sort of thing because, in my experience, the devil is in the detail and a little knowledge is a dangerous thing.
But I think there is a lot to be said for helping people build useful mental models. My experience is that people either have no mental model for how money moves or have models that are just wrong.
So anything we can do to impart some insight has to be a good thing.... but you're right: a little knowledge can be very dangerous :-)
I don't see any other way to teach ideas than to start simple, help provide intuition for the basic concepts, and build from there.
Maybe you should ask the author to add some further-reading references to the article?