This seems entirely false to me. To be honest it is so incorrect it significantly puts into question the rest of the article.
1. I have absolutely had managers motivate me to work harder. I have also had managers completely demotivate me and cause me to quit. How on earth can anyone who has worked in the industry for any amount of time say that "The only place where managers motivate people is in management books"?
2. Of course most of the facile strategies mentioned in the article (like 996, micromanaging, etc) won't work. The article then generalizes this to all strategies - but "if terrible methods can't solve it, nothing possibly can" feels like a shaky argument at best. A good manager understands this, and motivates by helping you understand how the things you are doing are actually critical to the success of the team and the company. (If success of the company isn't something you're interested in, then yes, it's going to be hard to motivate you.) A poor manager sabotages motivation in a hundred different ways - he makes you feel like your efforts are totally wasted, or fails to articulate why they are important.