Guess it depends on how long you've been alive.
"Back in the day"Penn State had starting QBs Milt Plum, Pete Liske, Tom Sherman, Galen Hall, and John Hufnagel (a star in the CFL).
But you are 100% correct that in the past 50 years or so, only Kerry Collins has been a regular starting QB (Matt McGloin might have gotten a few starts, but not many). Perhaps JoePa focused more on the running than the passing game; hence, all sorts of RBs started in the NFL.
Then came Hackenberg, McSorely, and Clifford. I think the latter might still be in the NFL, just not as a starter. We'll see about Allar.
The lack of developing a bona fide NFL-caliber QB might be the primary reason Penn State has not been a national champion since 1994 (yes, I consider that squad a NC). Michael Robinson was a superior leader and a solid dual threat QB, but he was a FB in the NFL.