I actually went to Vitality for a few months. It was okay, but honestly felt a bit like a factory. You go in, they give you the shot, and rush you out. Not a ton of actual guidance on lifestyle or nutrition, which was kind of disappointing considering the monthly cost.

Sifting does more than add air; it blends baking powder and salt into the flour so everything bakes evenly. @betty213 had it right with the teeth comment, but it's also about taste and texture in every bite. Without sifting, you might get bitter spots from clumped baking powder. I learned this after a batch of cookies had weird salty patches. Now I see sifting as part of measuring, not an extra step. It really does make a difference in how good the bake turns out.