|This page in a nutshell: Wikipedia editors will from time to time make arguments that are not grounded in any existing consensus on Wikipedia.|
Sometimes you will come across an editor authoritatively making an argument on a talk page that you've never heard before. If the argument is sufficiently removed from any existing policy or guideline, it may make you wonder, is that even an essay?
Wikipedia is governed by a large body of policies and guidelines that are often ambiguous, open to interpretation, and subject to change. However, these rules and norms represent opinions and positions that have been vetted by the broader Wikipedia community, and have decisive weight in discussions on Wikipedia talk pages.
Less authoritative than policies or guidelines are essays, which can be written by any Wikipedia editor, and are not necessarily reflective of opinions supported by community consensus. Nevertheless, citing essays is often useful in discussions, as it shows that at least one person has had this opinion before, and is a lot shorter than writing out an entire argument.
Oftentimes, editors who are new to Wikipedia will make dramatic sounding statements as if they were paraphrasing policy when in fact it is not even an essay. This could be because they've seen other editors make similar arguments about actual policy and can't even begin to fathom the labyrinthine depths of the projectspace, because of the Dunning Kruger effect, or because they really, earnestly believe that they are right. Regardless, you should bite them by quoting this essay at them because newcomers are delicious.
Alternatively, an experienced editor may make a similar mistake because they've either misremembered the actual policy, or possibly because a guideline changed while they weren't paying attention. Or it could be that they're intentionally misrepresenting policy because they're trying to get a leg up on you. Either way, citing this essay is definitely the best possible way to respond, as the purpose of Wikipedia talk pages is to maximize shame and frustration for all editors involved.
The following are examples of things that are not even essays