I don't think this is like looking up a reference. This article is a general guideline on how to be a good Principal IC, the thing you're supposed to already know if you're a Principal IC.
This is like reminding a top doctor "do differential diagnosis". Nope, top doctors already know this, it's redundant advice.
This is like reminding a good thinker they must think about things: they already know this and it's presumably how they got to the position in the first place.
That's a good point.
I think this article is a promotional piece for the author's personal brand, thinly veiled as advice for others. It's "look at what I know, and here's why you should pay me". These people love to talk about themselves.
It’s useful to have reference materials to check against, or for things you haven’t worked in recently.