Except that isn’t what admissions officers at elite schools using “holistic” admissions processes, i.e., just about all elite privates and some elite publics, say they do. I’m not sure what reason they would have to lie about it. And frankly I’ve never heard any description of the process by anyone who’s been involved in it that sounded anything like what you describe. It’s not nearly so mechanical, it’s much more subjective. The University of Michigan is obviously a public institution, but it uses a holistic process not unlike the top privates (except that Michigan is now prohibited by state law from considering race). Here’s a link to their actual rating sheet:
http://admissions.umich.edu/assets/docs/template-rating-sheet.pdf
“Secondary school academic performance” including GPA, test scores, class rank, and strength of curriculum is just one of seven broad evaluative categories. The other six are quite subjective. Three readers (“evaluators”), or two readers plus a “validator,” read the entire application file and give it a grade, Outstanding, Excellent, Good, Average/Fair, or Below Average/Poor, with plus or minus gradations within each of those. Then it’s forwarded to the entire committee which reviews those grades, probably has a brief discussion, and gives it a final grade on the same scale, coupled with an up or down vote on admission. Michigan is now selective enough (27% admit rate this year, 22% for OOS applicants) that probably only the “outstanding” and “excellent” applicants make the cut for serious consideration, and not all of those are offered admission. No doubt most of the applicants rated outstanding or excellent have very strong academic stats, but on this type of rating system it’s very possible that some applicants with less stellar academic stats are nonetheless rated outstanding or excellent, and it’s equally possible that some applicants with stellar academic stats come up so pedestrian or even negative on other parts of the rating system that their overall applications are graded “good” or worse, and they’re not offered admission. And indeed, every year you see a few OOS applicants crying on the University of Michigan section on CC, “What happened? There must be some kind of mistake; I have a 4.0 unweighted GPA and a 1570 SAT CR + M, Michigan was my safety, and I was rejected.” It’s no mistake; not everyone with stellar stats gets admitted, because in the big picture, with all factors considered, some other applicants with lower academic stats simply graded out better, or because there were so many outstanding or excellent applicants that they simply couldn’t all be admitted. And Michigan is now selective enough that it’s a mistake for anyone to think it’s their safety. It’s not as if there’s some clear threshold of academic stats that automatically get you admitted, with downward adjustments made from there for first-gen, economically disadvantaged region, legacy, etc. All that information–academic stats plus 41 other enumerated factors–are evaluated, weighed, and factored into the applicant’s rating by 3 independent sets of eyes, then by the committee, before a decision to admit, deny, or waitlist is made.