We also heard the same thing about USC in '00 before Carroll was hired as HC. But even if you squint, the Nebraska job isn't in the same stratosphere as Alabama, Texas or USC, as the only thing that prevents either of the aforementioned programs from annual National relevancy/National Championship contention is the coach itself, as top-flight talent will certainly follow. The "right" coach at Nebraska isn't enough anymore for mainly the reasons that Kronored pointed out. I also agree with bucksfan2 about the talent discrepancy preventing Nebraska from (as of today) competing with the big boys.
I wouldn't be so quick to shovel dirt on a coach who built Oregon State (Oregon. State.) from the ground up. Ironically, though, Riley's Nebraska offenses with the dual-threat Tommy Armstrong Jr. were pretty effective. Armstrong was far from Riley's prototypical QB for his system, though, to his credit, he tailored his offense to Armstrong's strengths and didn't pull a Callahan (or Hoke/Nussmeier at Michigan) and force-feed a system dependent upon a traditional drop-back QB upon a QB ill-suited for such. Riley, IMHO, is much more likely to land another Armstrong type than, say, a Sam Darnold type for Nebraska.
Conversely for Riley, if given the resources of Texas, Florida or USC (reportedly, Riley actually turned down HC job offers from Alabama and USC (twice), landing a top-flight, NFL prototype QB is exponentially easier, though he has done many times at Oregon State. I can guarantee you that a Riley-coached Florida offense wouldn't be stuck in the mud regardless of QB as it is currently under the leadership of the so-called offense gurus McElwane and Nussmeier.