Why scientists can't agree on the best diet.

I don't really have a problem with the article. It's a reasonable reduction, although I think paleolithic/low-carb diets are unrealistic if you stick to "mostly plants". Plant-based diets typically rely on grains -- when you remove this, it's very difficult to replace them without introducing more meat.

However, I think the more pressing issue is, even if we knew the perfect diet, it doesn't mean people want to eat it. Even if someone wants to eat a healthy diet, it doesn't mean they can make themselves eat it.

Self-control is a limited resource, and when overly prevalent junk food decimates that resource, most of us lose. If you want people to eat a healthy diet, you can't allow it to be easier to eat an unhealthy one. It's very noble to treat humans like gods with perfect free will, but in reality we're closer to animals. If we are to thrive, we need to adjust our environment so that it tends towards thriving.