My wife is a sparty and highly accomplished in life. I think the general quality of education she got plus her own native drive and intellect were fine.
My interest in sending my son to a "good school" in the top 100 of whatever category is just scoreboard of his/our success raising him. The ratings are likely just junk like you say. We've been to a couple campuses on our tours. Michigan is a very nice one. UVA also very nice. Some are just utilitarian.
In my own story...my terrible HS grades (we are talking Blutarski level gpa here) were mitigated when I finally realized I needed to get going: tested well on the ASVAB, joined the Air Force, got community college going, did well enough in University of Maryland overseas courses in the Air Force, got off active duty and applied for University of Michigan based on my CC and University of Maryland courses. I never had to write any essays or do well on the SAT. I showed up and worked hard because I gave a damn so it worked out for me.