Dinner, a shared affair not had standing alone over the kitchen sink because you’re just too tired to cook is often a light soup, salad, or fruit starter followed by anything you deem acceptable for dinner, because French people's food is considerably more variable than just brie and baguette, despite popular opinion.
Dessert is served directly after the main dish -- a yogurt and a piece of fruit often suffices -- but more often than not there will be some kind of cake as well, and occasionally cheese. Though a cheese plate is hardly present at every meal. When it’s all over, it’s over. No more food until the next morning, which gives your body about a 12 hour gap to reboot before you start the process over again.
French people are regular folks
Espresso, with its laxative properties, is typical after lunch, and dessert is often a piece of fibrous fruit and/or a yogurt. Fiber and probiotics are critical to proper digestion, duh.
All meals and foods are treated with the same reverence
Because food culture is so almighty in France, no one meal or food item is considered an “indulgence” and thus something to feel guilty about. Americans often “allow” themselves to eat something special, which does nothing more than glorify a certain food and encourage overeating when it’s made available. Indulgence isn’t indulgence if you just always indulge. Dessert doesn’t feel so important if you can just have it next time.