I certainly didn't "invent" it, since I didn't spread my idea to any others, but I did my own long before I ever heard of anyone else doing it, and long before there was flyertalk, or even the internet.
Around 1990, living in NJ, I nested 2 RTs PHL-JFK on TWA on consecutive weekends, purely to top off my account for enough miles for a trip to Europe, which turned out to be my first trip to Europe ever, and a great one to Munich, Salzburg, and Vienna.