I'm gonna have to call bull on this one...
My older brother definitely applied 2 cycles ago and was accepted off the waitlist in July. Furthmore, LSN shows waitlist acceptances have occurred over the past 3 years (including 8 this year, which, considering that LSN is not a complete sample and its still early in the summer, is pretty significant). Plus, there's people like me who have deposits down at other schools in addition to UM. Ggiven the above information, they must not be overenrolled, so more spots should open...