In the great kitchens of several decades ago, cream soups were exactly as we have just described: diluted, flavored sauces. In fact, what we now call cream soups were divided into two groups, veloutés (made from velouté sauce and finished with a liaison) and creams (made from béchamel sauce and finished with cream).
These methods were natural to large kitchens that always had quantities of velouté and béchamel sauces on hand. Making a soup was simply a matter of finishing off a sauce.
Modern cooks view these methods as complicated and have devised other methods that seem simpler. But most of the sauce steps are involved—you still have to thicken a liquid with roux (or other starch), cook and purée the ingredients, and add the milk or cream.