The chewing issue is part of it, but far from the whole picture. I recommend reading Jaws, as it's relevant to anyone whose kids will have dental work (which is basically everyone).

Part of the thesis is that braces and wisdom tooth removal are overapplied. People who disagree with that have to answer why ancient people and animals don't need similarly large amounts of dental work (answer: their jaws are a lot healthier than ours due to their environment.)

A related but separate issue in children is mouth breathing, and the chain of causation is also explained in the book.