^ I suspect there is a lot of truth to this.
The main problem that top colleges have is the overwhelming number of applications, the vast majority from fairly qualified applicants. It’s easy to pick out some with major hooks or achievements that clearly stand out, and to weed out those who clearly are a stretch; but that leaves the bulk of an admissions class to be filled from a very large pool of qualified unhooked applicants who aren’t that easy to distinguish from one another. Add in things like superscoring, test prep, grade inflation, paid college counselors and “buffing” of applicants, and it can be very difficult to sort through the noise, even for experienced admissions officers. Letters of recommendation are probably one of the areas where it is easiest to tell applicants apart.