It sounds like you are bitter. While I also question the "scientific" nature of an interview, I obviously don't feel as strongly about it as you do.
I think it is impossible to count on a lot of accuracy when people are involved. I have never been hired by Microsoft and when I was interested in a job, I never seemed to get past the phone interview. The times when I was not interested in relocating I would
get past the phone interview but decided against the day long ordeal. I have no way of knowing how it would have turned out. I always find it somewhat funny that my skill set changed very little in the phone interviews I failed and the ones I passed......
I have heard good things about the interview process, usually from people who got hired and I have heard the bad. For instance a
really really bright developer ran into an interviewer that seemed to be reading from a cheat sheet when asking questions. It became disconcerting for my friend because when he started to dig into the details of an issue it was obvious that
the interviewer had no clue about the particular area and when trying to work through the problem with my friend became flustered that he might actually be wrong. My friend never made it past that one person.
I am pretty sure he was qualified since the area in question was something he just finished perfecting on my team. Was he turned down because he butted heads with the interviewer.. Probably... Is he working on stuff he loves now... Yes... Life goes on.
I still think the root of the difference with interviews and hire and fire decisions are the people involved.