I don't know how common this sort of thing is, but in the comment discussion on this question, the OP (who's actually been a member for over three years!) defends his position that the question is on-topic by repeatedly pointing to the FAQ and insisting that his interpretation of it is "the" correct interpretation, and that the FAQ itself is in some way the "definitive" resource for determining what's on-topic.
It seems to me that this is (1) not an unreasonable assumption and (2) completely incorrect. As I put it in my most recent comment on the thread:
the FAQ, while certainly the most immediately visible/useful resource for newcomers, is not "definitive", while community consensus is definitive.
In other words, the nature and content Stack Overflow itself is determined by the users. (This is true of all Stack Exchange sites and, more generally, all websites. Heck, in a generalized form, it's true of all communities and essentially all ideologies. It's true of every communal undertaking.) We need new users to understand this and to respect the wishes of the community. I don't mean that they need to defer in all things to the whims of those who've been around longer or have higher rep or are mods or anything like that; indeed, we should encourage them to be an active part of the community and to help continually refine the definition of what Stack Overflow is or is not. But they do need to understand that the FAQ is not some golden standard of rules that are set in stone, and that they need to be receptive to the consensus of the community. So perhaps we should add a disclaimer to the top of the FAQ pointing this out? Something like the following:
This FAQ represents our best effort to characterize and explain the goals of this site; it is our sincere hope that following the advice on this page will help you become a valued and productive member of our community. It does not, however, define Stack Overflow; we as a community do that, and because it is a continuing discussion, our site continues to evolve in terms of scope and focus. We encourage you to take part in this discussion on Meta Stack Overflow, and we hope that you will respect the opinions of other Stack Overflow members regarding what types of questions and answers are or are not a good fit for this site. In particular, we would like to remind you that the final arbiter of what constitutes a good question or a good answer is a matter of community consensus, not FAQ interpretation.
This is quite a bit more wordy than it ought to be, but it gives the general flavor of what I'm imagining.