Fannie Farmer did invent measuring cups, though. Or at least, her Boston Cooking School Cook Book was an immediate best-seller that was the first cookbook to be written with precise measurements.

The "little bit of this, little bit of that" method of cooking learned at one's grandmother's knee was pretty much the universal method of teaching people how to cook in most cultures though most of human history. Still is, in lots of places. And if you look at most of the really early cookbooks, even up to the early 19th century, the recipes are incredibly vague as compared to a modern cookbook. That's because most of them are aimed at people who know how to cook --- the presumption is that the reader knows the basics already, and what the cookbook is for is to present them with new methods or fancy dishes that they might not have known about before.

That starts to change in the mid- to late- 19th century, because a few things are happening. Basically, for a long time the Venn diagram between "can read a cookbook" "can afford to buy a cookbook" and "actually does the cooking" had a very small area of overlap. In, say, 1800, if you were literate and could easily afford books you almost certainly had enough money to hire a servant to cook for you. As the industrial revolution went on, however, literacy rates started to rise, wages increased, and so more people could afford cookbooks, while fewer lower and middle class families could afford to keep servants. Also at this time, the science of nutrition was first getting off the ground, as well as public health. People start to become enthusiastic about the idea of applying these new, scientific discoveries to the practical work of running a home; proponents start to refer to their ideas as "domestic science" or "home economics". And the combination of these factors helps lead to the creation of the Boston Cookery School (where Farmer was the principle). Like its predecessor/competitor the New England Cookery School, the school was started with the idea of educating would be cooks --- both young working women and homemakers --- in the new scientific techniques would help them make healthier food in cleaner conditions with less drudgery. By bringing science to cookery, you could make cooking a respectable middle-class occupation. (And, not incidentally, codify a pretty bland, meat-n-potatoes, hide-the-garlic-and-pass-the-mayonnaise style of cooking as the healthy, nutritious, scientifically-endorsed diet of good old-fashioned Americans, unlike all these immigrants and their strange foreign obsession with spices and flavor.)

This is what Farmer herself had to say about it, in the preface to her book:

"At the earnest solicitation of educators, pupils, and friends, I have been urged to prepare this book, and I trust it may be a help to many who need its aid. It is my wish that it may not only be looked upon as a compilation of tried and tested recipes, but that it may awaken an interest through its condensed scientific knowledge which will lead to deeper thought and broader study of what to eat."

Unlike early cookbooks, in which recipes often consisted of little more that a list of ingredients, Farmer's cookbook starts with how to build a fire, and includes a section on how to measure different types of ingredients and the importance of doing so, as well as giving a conversion table that would help ensure consistent results from old recipes. She didn't literally invent measuring cups --- indeed, she mentions that most kitchen ware stores in her day already had them --- but cookbooks like hers did help spark a revolution in how Americans were taught to cook.