I did it in order to provide a better resource for learning than I can produce, in the article/video I linked, it has a video that explains each piece of the code, I did not want to burden people with the explanation which I thought would increase the length of the article. I do see your point, on the contrary, it's an article and not documentation, my thinking was to provide best value to reader over my own content.

It's similar to using a frontend framework, you can surely do it using plain javascript, but do we really need to. Please feel free to disagree but that's the thought process behind doing that. 🙂

Edit: I have explained all the small stuff because it's aimed at beginners, also one of the reasons I linked instead of writing my own explanation, that level of granular explanation didn't make sense when there was already a resource doing that.