One big issue is that industry jobs in some areas increasingly expect academic excellence in the shape of "publishing in top 3 conferences" for example.
Someone who only published in 2 top conferences is obviously not worth anyone's time. But 3, now we're talking.
Top people come from non-top schools, and lots of non-top people from from "top" schools. And some top people come from no school at all.
And intelligence agencies are government mandated, not marketing made. Or at least I haven't heard any marketing from the NSA saying how selective they are in admissions (as if that means anything).
For some reason that seems slightly non-optimal.