Uh, no. I don't know where that quote is from, but it's bogus. If there's a meta thread that shows consensus on an issue, and it doesn't contradict an SE policy¹, you can take it as a site-wide policy. What is linked from the site FAQ is the most important stuff that new visitors should be aware of, and what is tagged faq on Meta is less important stuff that comes up often.
All meta discussions are to be taken into account whether consensual of not. If there's a near-consensus, you can treat them as policy, in that for example moderators will act on them. If there's no consensus, they are still relevant in that they show arguments that have been made on a particular issue, and they may be updated to deal with a new example of that issue.
One thing that does distinguish most meta threads from policies is that just because an answer has a lot of upvotes doesn't mean every word of it is policy. Upvotes show agreement with the general trend of an answer, but not necessarily with every detail. Going with the example in your question, I would say that “It's NOT OK to say that "any answer of a 'bad writing'/'plot hole' type" is a bad/inappropriate/offtopic answer” is a generally agreed-upon policy, but the specific delay of “2-3 weeks” is not policy. Mind you, that particular issue isn't really conducive do policies, since it's mostly about answer quality which is decided by voting, and voting is a personal choice.