Okay, it may well be the case that Harvard and Yale aren't the best law schools or whatever; but there aren't a lot of objective measures the adjudicate the question (bar passage rate being high-90s for most, say, t25 law schools; law review productivity and moot results being confounded by the same problems you mentioned; subsequent postings being confounded by the same problems you mentioned; pre-law school stats like undergrad GPA and LSAT being a bad measure) -- so at the very least let me stipulate that there is a wide conventional wisdom that Harvard and Yale are among the best law schools in the country and that the kind of students who get appellate and SCOTUS clerkships are among the best students at those schools, even granted they are also wealthy, connected, and some of branding is a shell game.
My interpretation is that it is possible for clerkships to both be relatively meritocratic and also a pissing contest between Harvard and Yale because (shocker) the most talented law students do tend to go to those schools.
