That old joke is just a joke. The doctor who finished last in his class isn't nearly as likely to get the best gig straight out of school as the doctor who finished first. The best grades from the best colleges do matter for entry level workers who want the best jobs available.
The best from med school may get the best positions in the best areas. I am sure there are a few exceptions, but the interurban hospitals in two cities where I worked had some pretty marginal staff. Especially during the collapse of the medical industry under obamacare, the standard quality of care for the masses will look a lot more like Parkland than like Baylor.