The article is very humble, but in my view, seems to go a little too far. "You can reuse code with inheritance. Absolutely crazy. Brilliant. All of this blew me away." Honestly?
Thats a very critical point that you just have to understand, to "get". Many people know and learn about object oriented design, but when tasked to actually write a program based on these principles they will often revert to code where they make distinctions based on the type of what they have been handed. TLDR: dynamic_cast is bad design
Using static conditions rather than polymorphism seems to just be a common thing that people tend to do, regardless of skill level or quantity of experience. It's not uncommon for people just not to think of using polymorphism, if the objects in question wouldn't really model any particular kind of object as such (they're just there to provide a table of function pointers). This says nothing about the quality of their code, or the general OOness of their designs, or the number of digits in their IQ.
It's a bit of a shame, because I've found code to be reliably improved by using objects as simple tables of function pointers. The same is less often true for using objects as models of things.