For one, it is not "shallow breathing", it is light and calm breathing! Don't misquote me! Also, if you understood actual scientific breathing physiology, instead of telling us your opinions, than you would know that the more you breathe the more CO2 is released which causes a whole cascade of symptoms, many which parallel anxiety. One of the main problems people with anxiety have is overbreathing and hyperventilation. Keeping the breath calm, light and relaxed is how to not offset the CO2/O2 balance and how to not trigger more panic and more adrenaline. That is not shallow breathing but simply not overbreathing. You can breathe into your abdomen and still keep it light, calm and relaxed with a nice steady flow. This technique works and you may want to understand things before chalking this off of just some guy's opinion.