To be fair some of the seeds of bias against new hires were sown during the "I didn't go to nursing school for this" attitude not a small number of new grad hires brought with them starting around the early 2000's.
Hospitals did hire new grads and many in the nursing service including educators, floor and staff nurses gave their best to orientate and train. What many were often met with were new nurses with widely varying skills and education including some barely competent in core nursing skills if they were aquainted with them at all. Others still had either no clue or didn't want to know just what the nitty-gritty daily duties of a RN were. When faced with the reality of these expectations you had 1 in 5 if not more new grads either leaving of their own accord before their orientation ended or simply were let go. Such a model was simply not sustainable and it therefore should come as no surprise facilities started to take a look at the quanity and quality of new grad hires.
Happily for hospitals (but not so much for some others) the recent financial/economic crisis upended the healthcare world in ways that are still being felt today.
Hospitals began closing or consolidating staff due to mergers. Experienced nurses who had been quasi or fully retired re-entered the nursing workforce full time. Those thinking about leaving reconsidered out of real or other financial concerns. Bottom line is for many areas of the USA there was a surplus of experienced nurses which decreased the pressure to hire new grads. Couple this with changes in staffing (movement to 12 hour shifts, call offs, etc..) and better utilization of nursing service (fine tuning staff levels to pt census, scheduling nurses to report for duty closer to when needed for certain units such as OR, etc..) and hospitals found they could get by without having to hire many new grads. Remember a bulk of the hiring of nurses was to replace those whom left for various personal reasons: marriage, children, retired, etc.. When any drop off in those levels occurs you have the "clogging up" of the system the CNN article speaks of. In short those wacky nurses aren't behaving the way they ought in theory. Suppose we could put this down to the unstable nature of the female. *LOL*
How long all this will hold together is anyone's guess. But as long as the hiring and orientation of new grads remains a net cost to hospitals they are going to find ways to lessen that exposure.