The article is both true and irresponsible. It's true that diet is more important than exercise for weight loss, probably because it's easier to cut a couple of Cokes a day than to run 3 miles, and both equal roughly 300 calories.
But it's irresponsible in quoting the medical/scientific literature very haphazardly. And it's as much an opinion blog as a journalistic report. And it doesn't put enough emphasis on the health-enhancing benefits of vigorous exercise.
Many health-nutrition experts now believe it makes more sense to try to get people moving more than to try to get them to eat less. The research on the benefits of exercise is very strong, and much of it extends to those who are overweight. If you are fat but fit, you can still be very healthy.
To me, the biggest fault in the article is not exploring reasons why someone might want to lose weight and be thin.
If for your health, you can just exercise (as above) and not worry too much about your weight. If to look thin for cultural reasons that emphasize this look, just smoke a lot of cigarettes. That will kill your appetite, and you'll get thin. (And eventually kill yourself.)