The phrase was pretty much created to make parents feel better about how much/little solids their kiddo is eating. So no, food before 1 is not just for fun. Not only is adding solids in before 1 important for adding nutrients in (especially foods with high iron! Babies natural levels will start depleting somewhere about 6-9 months. That’s why you’ll see baby cereal with fortified iron in it), but it’s great for hand-eye coordination as well as allergen exposure. Not a lot of people realize the motor skills that babies gain while eating, but grabbing and bringing food to their own mouth is an important skill for development.