This article could be summarised as "abstract only when you see a clear need to", something that seems to be the exact opposite of what a lot of programming courses teach; especially those dealing with object-oriented design. I think abstraction should be viewed not as a technique to be applied generously and whenever possible, but a necessary evil, resorted to only when nothing else can simplify the code.

A bonus of this style is that it often also makes the resulting code more efficient for the machine to execute, reducing the need for optimisations later.