Bear in mind the next thing the article says is >(And of course there was no Unity or Unreal Engine to license.) But advice like "don't reuse" and "use an ext

Bear in mind the next thing the article says is >(And of course there was no Unity or Unreal Engine to license.) But advice like "don't reuse" and "use an external framework", actually have a common root because the difficult thing in programming is not banging out code, not even when you have your QA in place. The really hard thing is getting knowledge: figuring out the right thing to do and how to do it. Once you have figured it out in one app, you can do it again only better in the next app you write. You are re-using knowledge that is stored in your head. But when someone writes an engine, they are also storing knowledge, but now inside code. Again, knowledge is being re-used.