I'm actually more interested in the parts he chose to ignore, because all the replies are about things that every programmer learns in his firsts 2-3 years of work -- so nothing especially insightful, just common field knowledge.
I'm inexperienced in any language that I did not write at least a mid-sized program in, on every system that I haven't used yet and on every program whose code is not intimately known to me.
There is 'general' experience that applies equally across the board and that experience you either have or you don't have it, but for the rest we are all only as experienced as we are familiar with the tools we use to do our work.
Try switching from your 'favorite language' to one that is your least favorite and making some headway, versus the 'experienced' (but relative newbie) on that platform. You won't stand a chance.
Programming computers and computer science has become too large to still be able to be an 'all-rounder', you can't do all of 'embedded systems', 'web apps', 'operating system kernels', 'algorithm research' and so on. And if you can then you're either not human or exaggerating ;)
But, generally speaking, you are experienced. What you say is of course true, but that's what makes the linked article even less interesting. If I wanted to learn more about new language, new system or new tool, I would rather ask "what should every foo language programmer know about foo". The question posed on stack exchange asks about nothing specific. It's like one asked "what should everyone know about life?" and got replies "always remeber to brush your teeth and flush the toliet". Meh.
If HN was the mathematics forum, one would read and comment news about research in number theory and algebraic topology, not high school math, for it is not particularly insightful and entertaining.
Seriously? You're going to take huge swaths of things off the table to try to force the discussion the way you want it to go?