not sure what the official name for this particular cognitive bias is (feel free to enlighten me)

I've usually heard it discussed in terms of the Dunning-Kruger effect, although that seems slightly different than the model the SMBC comic describes; subjective certainty isn't quite the same thing as willingness to opine, although they're certainly closely linked.

My own Mount Stupid was highly general and came pretty early; as an older child or a younger teenager I was prone to holding forth on anything I had a model of, even if I'd come up with the model on the spot based on anecdotal evidence. I generally got away with it as long as I was speaking privately with groups that didn't have much collective knowledge; the appearance of certainty can give you a lot of intellectual status.

I don't think it fully went away until I'd lost most of my political partisanship (motivated thinking seems like a great way to stay on Mount Stupid), but the popularization in my mid-teens of modern Internet forums (BBSes and Usenet had been around for a while, but I hadn't discovered them) probably drove the first nails into its coffin. Suddenly intellectual status wasn't defined by being able to say the most reasonable-sounding thing at any given moment; statements were persistent, and could be effectively refuted well after the fact. Basic fact-checking became a necessity, and actual research became a good idea if I was broaching a contentious topic. Eventually it got to be a habit. I'm probably still stuck in a few local maxima on various topics, but even the foothills on the far side of Mount Stupid are a lot less embarrassing than its peak if you spend a lot of time with persistent media.

Rationality techniques are helpful, especially in estimation of confidence, but knowing to use them seems to be more a matter of style than of knowledge; it's all too easy to treat rationality skills as a means to winning arguments. This certainly falls under the umbrella of rationality, and the Sequences discuss it in a number of places (the first one that comes to mind is the arguments-as-soldiers metaphor), but I'm not sure I'd call it a skill as such.