Beaten egg whites is the “correct” way to make waffles, and they even make better pancakes. But I rarely make waffles, because the best recipe I ever found had enormous quantities of butter and baked up so light and crispy that I had to eat *lots* of them.
Beating egg whites probably is a bit more intimidating for the random cook than using baking powder.
Cooking/baking is such a huge field than even acknowledged experts can make some claims that can’t be defended. CI, in one of their pancake recipes, claimed that pancakes made without baking soda will not brown, which is absurd. I took their recipe, replaced the baking soda with baking powder, and turned up the heat on the skillet, and they brown just fine.