OK, those are fair points. A programmer with ten years re-writing the same COBOL or VB.Net programs over and over again still won't have the background to pass a basic data structures course, never mind learn OS dev. No amount of Python or Ruby programming will make you ready for OS dev, I don't disagree.
Rather, what I was offering was a heuristic, a minimum boundary that would apply for most people. I am really saying that someone with
less than ten years experience in general won't be ready for OS dev,
even if they spent a large part of that time on C and assembly. I was saying 'Jacks or Better to Open', where 'jacks' is 'a significant amount of low-level programming, and a several years of programming in general'. It isn't a hard and fast rule, but... well, how many here wouldn't have been better off polishing their skills, practicing at coding, reading up on algorithms and general programming theory, etc. for several more years before starting? I know I could have.
Still, it is a valid point, and I have changed to read as follows: "A decade of programming, including a few years of low-level coding in assembly language and/or a systems language such as C, is pretty much the minimum necessary to even understand the topic well enough to work in it."
The real problem isn't even lack of skill and knowledge, it's the
Dunning-Kruger Effect. This group, like many others, gets an endless procession of novice developers who
don't know they are novices. Too many would-be OS devs think they
already know everything they need to know about programming, and are offended when we tell them that they haven't even started learning yet.