Eggs are great.
You see eggs in lots of dishes in American cuisine. Egg salad made from hard-boiled eggs is an American cookout standard. Fried eggs often go on burgers; poached eggs frequently find themselves atop sandwiches and salads. Scotch eggs are a frequent side dish or appetizer. But in American cuisine, eggs are almost never the focal point of a dish.
Except at breakfast.
Omelettes, scrambled eggs, and quiches abound at breakfast and brunch.
At what point in history did eggs become a "breakfast-only" main dish?