[aroch]

>You are underestimating inertia and unwritten rules. It's widely considered unethical (or at least frowned upon) to join a PhD program and intentionally quit with a Masters.

From the school/department's view, yes; from the perspective of the student I'm not so sure. Over the last few years, many of PhD programs I interacted with (In the biological and chemical sciences) were increasingly mastering out more students than they were passing through comps/quals. It has gotten to the point where students are intentionally failing their comps/quals so that they can master out. Going this route means you didn't have to pay the master's tuition and were on a stipend the entire time -- better than paying the master's tuition and having to scrounge for cash.