Agreed. This is one of those topics where what actually occurs, and where what people on SDN want to happen are not in line. Premeds who slave throughout school to get their 3.8/38 don't want to hear that this can all be taken away by someone who interviews a bit better. But you'd better get used to this. You will meet folks in med school who didn't have the best numbers on their interview day, but are simply very dynamic in person. You will also see plenty of people who get tons of interviews with great stats and get passed over. We see this EVERY YEAR on SDN -- folks with simply amazing numbers whining about how their interviews went okay and yet they got waitlisted at every school. Why? Because simply not blowing the interview isn't the standard -- you need to ace it as much as you needed to ace all the prereqs. I stand by my above statement of what is common, having been through the process and having had plenty of discussions with adcoms and deans at multiple schools about the process both school specifically and more broadly over the years. I've raised this point almost annually, and many folks who have yet to go through the system cry "foul", but each time I talk to people on the other side of the process, they reinforce my statements.
Flip's suggestion that it makes no sense that someone with a "mediocre GPA/MCAT/ECs" would beat out someone with better stats ignores the fact that the weed out for these factors occurs prior to the interview, in choosing who gets invited on interview day. Massive cuts are made just to get to the number who get invited. Programs are getting as many as 10,000 applications, and can only interview a small fraction of that. So guess what -- everyone with "mediocre" stats doesn't make the cut. That way, everyone on interview day shows up at least potentially acceptable to the school. And from there the interview makes and breaks you. And I would take things like ECs out of the above statement, because as mentioned above, ECs often become fodder for interview discussions -- if you don't have any experiences, you make a lousy interview. So these do play in, even though not counted again. Not so with numerics though.
And why is the interview so important? Because once you get past the basic science years, medicine is something like 80% interpersonal skills, and 20% knowledge based. Thirty years ago med schools were much more "by the numbers", and the public ended up hating the type of doctors being produced, so the field sought to change that, not only by emphasizing the interview, but also to incorporate more nonsci majors, more nontrads, more minorities and women into the field. This is part of the changing of the face of medicine, from number driven scientist males who cannot interface with people well, to a more empathetic, touchy feely, multicultural, multigender group. Medicine is a customer service industry, and how you are in person is going to decide whether patients perceive you as any good. Shows like House are amusing, but in real life nobody goes to a doctor who acts like House. Forty years ago they might have no choice.