I think this conflates "smart" in the sense of "raw ability to reason" with "smart" in the sense of "knows the intricacies of how things work". Or, as my uncles might have said, "book learnin' versus real knowin'".
In fact, even in the example given with respect to Ruby procs and lambdas and returns and whatnot, clearly the author hadn't "gotten things done" in that area (by his own admission, this isn't snark).
So to me, the real point is that thinking you've worked everything out from first principles doesn't mean you actually understand all the implications of the interactions in a complex system. That's the mistake I made as a young man, certainly, and it took me years of learning the hard way that I wasn't always right.
"smart" and "gets things done" are sufficiently vague that they can mean whatever you want. If I say "So-and-so is smart, however X," the reply can always be "Well, if X then so-and-so isn't truly smart" in the No True Scotsman sense.
This is why I tried (perhaps poorly) to be specific and talk about smart in the sense of mathematics.
I think in the instance you described you were and weren't being smart in the sense of a True Smart Scotsman.
Mathematic smarts isn't always enough to know how something really works. But I still think you were smart enough to realize you might be wrong and to double check how it really works.
Also, you have the GTD mindset to accept how Proc works and try to learn from the experience instead of obsessing about how Proc is broken and ruby sucks.
In fact, even in the example given with respect to Ruby procs and lambdas and returns and whatnot, clearly the author hadn't "gotten things done" in that area (by his own admission, this isn't snark).
So to me, the real point is that thinking you've worked everything out from first principles doesn't mean you actually understand all the implications of the interactions in a complex system. That's the mistake I made as a young man, certainly, and it took me years of learning the hard way that I wasn't always right.
Also: there's always a relevant XKCD. http://xkcd.com/793/