French "haute cuisine" originates in aristocratic circles in the 18th century, some time after the Russian novelty of serving meals in courses (rather than as a kind of buffet or mezze) was introduced to France. It catered to a class which ate white bread and sugar - and had no teeth except those bought from peasants who ate hard brown bread and a great deal of (mainly) wild fruit. This class liked bland and mushy food raised in the Paris area (Ile-de-France and Upper Normandy). The diet thus leaned heavily on butter, cheese (especially local Camembert and Brie) and cream. Butter, cream and white flour were used to make sauces which made chopped-up meats swallowable by the toothless.
After the Revolution of 1789 the rising bourgeoisie took over aristocratic tastes (and aristocratic cooks) with a vengeance. They started eating song-birds, foie gras and other delicacies of the degenerate and amoral. Governmental centralisation by Napoleon ensured that Paris was the fount of all knowledge and fashion. But it took another 100 years for Parisian bourgeois cuisine to penetrate the whole country. Today there is very little indigenous, local cooking. Those recipes which are claimed as regional are Parisian versions or perversions of ancient dishes. Right up to the First World War most people in France ate very little meat. They lived from hard bread (sometimes baked only once a year) and bad wine (since water was often dangerous to drink), wild fruits and herbs, and what they could grow in their 'potagers'. No French people, not even rich Parisians, ever abandoned the traditional eating of bread, hence the strange habit of eating quantities of bread together with quantities of other food. Since bread is often filling, the Parisian baguette came about: a kind of bread with very little bulk, taste or nutritional value.
All this said, it should be noted that the most common dish eaten in restaurants in the 20th century was (English/American-style) Steak & (Belgian) Frites or 'French Fries'!