First of all, Laurie your RIGHT in you argument. Elbows are not Mostaccioli, BUT some Italians have different terms for their dishes.
Each style of pasta is made to suite a different sauce that it will be used with. A true Mostaccioli style of pasta is one that is a lot like Ziti, but larger, without lines, so the Elbows are smaller but have no lines. The thickness of the sauce is best used without line in the pasta.
To understand the name of dishes in Italian cooking is wild when it comes to home cooking. It's a little better in restaurants, but that depends on the owner. Now the Chains have their own way of doing it. If you have eaten in a family style restaurant they are more close to the right way of classic cooking. (NOT ALWAYS) The best place I know is Vegas gourmet Italian restaurants. Most of the chefs are from the old country, so if your there spend the extra bucks and ENJOY.
Joe