The reason is pretty simple: very few people have a disposable Mac. About 90% of the time, the Mac people want to install Fedora on is their personal laptop. So of course they're not willing to test installing some random pre-Beta nightly snapshot and tell us if everything explodes. We also can't i) easily or ii) legally (AFAIK) install OS X into a VM on non-Apple hardware for testing.I don't see why people should not have a disposable Macs but is "normal" to have a disposable PC. Also, AFAIK, Mac users tend to substitute their machines more often than PC users (at least statistically speaking), so many of them should have a 2-3 years old machine laying around.