The job market works both ways.
My alma mater, a PhD-granting institution (R1) ranked in the 70s, doesn't have many faculty members from the upper tiers. In fact, only two faculty have PhDs from top-ten schools. A few years ago, they rejected a well-published Yale applicant for someone with a much less prestigious degree for reasons of "fit."
I don't think this kind of story is at all anecdotal, either. If it were--if going a school outside of the top 25 spelled doom--then programs like Minnesota, USC, Penn State, WUSTL, SUNY Buffalo, and Washington would be considered completely worthless. And yet, in the last few years, I've encountered recent up-and-coming scholars from all of these programs who managed to land fantastic jobs.
Oh yeah, that Semenza guy that everyone keeps quoting? Got his PhD at "low-ranked" Penn State.