I think their opinion is that fries/salad is a lazy choice of sides to complete a meal. A traditional meal is usually a combination of protein, starch, and veg. In that regard, steak+fries+salad is a "meal", but it's definitely low-effort and designed to make people not hungry as cheaply as possible.

Good restaurants will create thoughtful sides that truly add to the dish, so it doesn't feel like you're eating "steak and some other shit".