We also have a "mythology effect" but with a twist... It applies to companies alive and thriving today (unlike an urban myth where no credible source can be found).
Consider stories from early days at Apple and other companies where no one was older than 30, then 35, then they stopped reporting. That was mid-1980's and into early 1990's for other businesses. Then it repeated in 1999-2000 with brand name dot com start-ups. It's happening today with upstart game companies that consider 7 years experience to be senior level.
So this meme persists on some level with each wave of newcomers (e.g., college grads).
I suspect that the effect gets compounded by newer programmers beginning with relatively newer languages and tools. It's easier to master a language/tool when it grows up with you. I saw this when C became mainstream, with Python, with Ruby, and currently with Clojure, Scala, etc.
When C was blossoming outside of Bell Labs (following Peter Norton's "Industrial Strength Programming Language" article in mid-1980's), when Python was merely v1.5 in 1999, when Ruby wasn't yet associated with Rails-- the majority of people using these were young, looking for an edge and seeking to avoid pitfalls associated with urban myths about what came before. (e.g., pre-ANSI C satisfied concerns that Lisp was slow and required special hardware-- myths circulating college labs of late 1980's)
It's easier to debunk these things today, thanks to the programming languages shoot-out, stackoverflow and threaded comments such as on HN. Due to these reality-check possibilities, we may hopefully put such systemic ignorance behind us.