While I am sure that there are many individuals who now come in with more code experience than the typical college student in the early 90s, there is a significant aspect of "are you mature enough to teach?" and "do you have enough experience to help students that need help?"
Assisting teaching a class, maybe. But looking at the quality of the code I wrote and the advice I would give based on that code that I wrote, I would be very concerned for the future prospects of anyone who I taught when I was 21 and looking for a summer job.