While I have no doubt what you say is true at some schools, I know that it is not universally the case that the committee fully reviews all applicants. My research advisor told me that as a grad student she and others worked with the admit committee and their job was to read and comment on the applications. She also said that while a professor would look at their comments (multiple grad students would comment each paper) before any decision was made, the professors would remove many applicants from the pool from the comments alone before the actual committee reviewed them, and this was at a top CS school. So if there were a lot of comments like "very low GRE and GPA, but good research", I could see a professor at a top school tossing it before taking it to the committee since there will likely be a large stack of "good GRE, GPA, and research" in the pool. Obviously grad students have more knowledge as to what a good applicant should look like over a secretary or something, but they aren't quite the professors of the committee who have done this several times so for people who have less balanced profiles, it might be hard to make it through any kind of early elimination.