I agree 100%, Tom. I often hear that "We bought this CAD software because the majority of customers we deal with use it." Although I, too, dealt with customers, machine shops, and second-party vendors who have asked for a certain native file or two, I have never noticed a trend regarding a problem because of the type of file I sent. In fact, I have sent many types of files(mostly IGES, X_T, SAT, and STEP) to these people and never once received a call back, telling me that the generic file "didn't work".
The act of demanding native files does and will stifle creativity - kinda like asking a left-handed .400 batter to bat righty - not a good idea if your goal is winning!
Let's face it, no single MCAD software will ever mimic Microsoft and "dominate the world". My advice to those who are on a mission to force everyone to use what they use for no other reason than for their own convenience - wake up and smell the coffee!