They’re still only marginally useful because the SAT is too easy. Harvard has enough applicants with 99 percentile scores to fill their incoming class multiple times over.
Plenty of high school graduates have the 4.5 GPA and a snazzy personal statement and all the right "add-ons", but aren't actually equipped to succeed at Harvard. The SAT is plenty useful to evaluate that.
That's a feature, not a bug. If everyone has a Harvard degree, nobody has a Harvard degree. A lot of the worth of one derives from its exclusivity, and the cream of the crop you meet there because of that exclusivity. I'd posit that the difference in the quality of the education itself received between Harvard and a good state school isn't worth talking about.
Harvard freshman class size is 1700, but there are also a number of other schools at the same tier of Harvard (off the top of my head, Princeton, MIT, U Penn, Stanford, Yale)