I don't think there's any arrogance in the statement. It doesn't assume others don't think. It's simply observing that most blog posts and how-to articles show the final result, but not necessarily the steps that were needed to get there.
I'm not really sure I understand what you're saying and/or asking.
As far as I can tell, the statement in question was simply saying that showing the steps to come to a solution is rare, and also that it helps to teach how to think (how to solve a problem). I guess don't see where the arrogance lies.
