Pretty well every rule you have here is wildly oversimplistic. It makes me believe that you have only worked on toy programs.

Only one level of indentation forces you to create hordes of tiny little functions with no clear meaning. "Avoid excess indentation" is good advice, but "only one" is crazy.

I can't even imagine what possesses you to get rid of else statements - your explanation makes no sense.

9 times out of 10, wrapping primitive types makes for more, harder-to-read code.

The Law of Demeter is important. "One dot per line" is ridiculous.

No more than two instance variables per class! If one thing were to prove to me that you've only written toy programs, this would be it.

Complexity actually exists in the real world. You need to deal with it in some intelligent way, but pretending it doesn't exist is just silly.

I think people overuse getters and setters, but to avoid them completely is again madness. What happens when logically, there must be a side-effect when you change some value?

And I have to go back to "no else statements". That just makes your code longer, slower (because inevitably you'll have to test the same condition twice), and harder to read.

Your idea that you should replace else statements by polymorphism is crazy. Polymorphism is a very powerful but also a big and heavy tool. It should be reserved for when there are actually different classes with the same parent.

Overall, I can't even give this a single clap. I would strongly recommend to programmers to not read this article as it will give you wrote ideas that will not only make you do a bunch of pointless work, but make your code harder to read too.