Why do you think this would have adverse selection against the top of the pool? I can clearly see how it would act a barrier to application for the bottom candidates (a good thing for the company), and I can see how it would reduce the number of applicants who are applying "everywhere they can think of" (also probably good for the company in terms of getting a more qualified [in the sales-conversion-rate sense] base of applicants).

In my experience, the very top of the applicant pools aren't applying to a particularly large number of places.