The article discusses the problems of a hamburger menu but doesn't address why its used, and then goes on to suggest a solution which does a worse job of what the hamburger menu is actually designed for.
You asked "Why put a link to the footer in the header which contains links to other pages when you can just put your links directly in the header?" The article answers this question, quite clearly and in detail.
Ironically it seems like you didn't read my comment. The first line explains why thats a bad solution, because its just moving clutter around the page but with extra steps
I read it, it just doesn't make sense. There's nothing harmful or disruptive about having lots of links tucked away at the bottom of the page, out of the way. Hiding those links in a hamburger menu doesn't fix the problem, because there's no problem to fix. But it does introduce several other, more significant problems, which are described in the article.
The article discusses the problems of a hamburger menu but doesn't address why its used, and then goes on to suggest a solution which does a worse job of what the hamburger menu is actually designed for.