I get your key point, and I agree there's material subjectivity in most collegiate admissions deliberative processes and offer decisions. I don't, however, concur that one can "score perfect admissions tests and have straight As for all 4 years of HS but that still will never guarantee your acceptance into a school." I don't because all four of my kids did almost exactly that (4.5+ GPAs, 1550+ (SAT)/32-36 (ACT) and 4s and 5s on their AP exams is close enough to what you have in mind, wouldn't you say?), and they did it at some of the nation's most rigorous high schools. Each of them received admission offers; thus I think unfounded the notion that one can perform that ably and not be "[accepted] into a school."
On a slightly different note, one may not receive an offer, however, from one's first-choice school. That happened to one of my kids -- that was hardly his first nor last disappointment. He "got over it." And why wouldn't he? His goals were to obtain admission to...
- a school that had a strong program in the discipline they thought, upon matriculating, he wanted to study, and to
- as good such a school as he could afford (given what I was willing to pay + whatever scholarships he earned) without assuming a debilitating debt load and without compromising his available discretionary spending. (He and I recognized college is about so much more than academics, and that "more" costs money, sometimes a lot of it, but we both knew I wasn't willing to be an everblooming "money tree.")
And that's really all that matters. Some might say it's more than what matters. In any case, so long as one gains admission to a decent school, it really doesn't matter to what school(s) one didn't obtain admission.
Lastly, each of my kids had the prudence to form a backup plan, even as they had laudable academic and extracurricular performance records. Part of that means applying only to schools at which one is willing to enroll. That way, no matter where one goes, one'll be fine with it.