Another point: in the old pre-draft and pre-expansion days we used to see good QBs sit and wait for their chance to play. Steve Young waiting for Joe Montana to move on. Danny White waiting for Roger Staubach to move on. We don't see that these days. Instead we see teams take a hit while looking to find a good enough QB. Even the Manning -> Luck transition included a "Suck for Luck" year.
Aaron Rodgers waiting for Brett Favre
Jimmy G waiting for Tom Brady
I think it still happens.