I do not think we should ban lore questions as a whole. Let's first look at what we currently prohibit. We've basically got two kinds of major reasons to marking subject matters as off-topic to us. Either they're mechanically incompatible with our Q&A system (ID, gamerec, shopping), or they sit outside the scope of our expertise (design, news). There's also the obviously-not-gaming stuff and then there's piracy which is kinda all kinds of not happening.
Where do lore questions fit into this?
There isn't a mechanical issue. Back in the gamerec debacle, I classified the major question classes we deal with, one of which is "fact finding". It includes game mechanics questions as well as character/plot. In a sense fact-finding is just problem solving where the problem is "I do not understand this concept", but it's identifiable enough to be its own superclass. This division exists largely across the entire network, not just Arqade. Mechanically, lore questions are identical to game mechanic questions in performance for this department, and are typically rated appropriately to their quality.
The main difference between lore and game mechanics is the source of the fact - whether it's in the story of the game, or if it's in the workings of the game. They draw from different expertises, which brings us to the second class of off-topicness. But first, an intermission quote, from a thing I wrote originally as a response to a recent Meta:
Consider news and design questions. It isn't sufficient that there exists a public statement that answers the question - this is, among other things, out of our control to know. That the designer has out and said "We designed it for this reason" doesn't make a question answered by that miraculously on-topic when a question of equal substance that doesn't have an official answer decays. This being outside our measure of expertise is why we blocked those subjects even if we're able to find the answers - we're not the place for it.
The point of this passage and its surroundings was to highlight that "there exists an answer" is a poor metric to acceptability. It's an incompetent measure that makes it difficult for both askers and enforcers to judge a question's validity, and both need to be able to know with relative ease the validity of a question. That passage also refers to the two identified off-topics that are outside the scope of our expertise. So let's boomerang back to that as applied to lore.
Does lore fit within the scope of our expertise? I believe it should. It is rather entrenched in our natural expertise similar to game mechanics. You can play a game and remain ignorant of why all the cats have no legs or arms in the same way you can play a game and remain ignorant of how much each point of strength contributes to your damage. Both have the easy knowledge observed from normal gameplay and then extra knowledge done by going out of one's way with analysis of the game. They're both understandings of facts that people do ask about. And both mechanics and story have questions that are inappropriate for the site even if the main class of questions is acceptable, typically by going out of the bounds of the game's expectations.
To game mechanics, this is wondering about mechanics beyond the scope of in-game means, as typically achieved by glitches or hacking. It's straightforward to identify if someone asks how to modify variables that cannot be manipulated, but there are some things may look hacky so we basically have to use our best judgment when a question asks how to accomplish something that doesn't seem possible in the game. Story is in much the same boat, but wherein the knowledge is obscurely derivative or is present in external reading material. In both cases, the validity can't properly be judged on account of the source and its presence in the game - knowing that a weird fact is revealed in the game is as odd as knowing how to use odd mechanics to break into someone else's sequence. This brings us to "the answer noting that it is in the game" being the validity call, which is a poor experience and we should not operate for this.
We thus have to determine acceptability on a different scale than whether it's in the game. Which we'd probably pick a metric like "relevance" and make judgment calls. There's a division between clear, relevant, and reasonable information found in the games versus obscure and/or banal trivia, and that applies to both mechanics and lore. If average players look at the question and thing "Who cares!?" then it's not so useful to keep, compared to one who sees something and goes "Huh, now I'm wondering that, too." and gets voted on. Unless it's quite painfully obvious to those in the know that the question is irrelevant, then we can swing in as normal.
To wit, instead of taking a proactive approach of closure for grey areas, clearing the less-than-not-even-useful could be handled by the automated process of abandoned-and-unwanted-question-cleanup if we just leave them be. I don’t know that we can measure the effectiveness of this on existing data due to all the fighting which, as it were, inspired this ultimatum discussion to turn up. So we’d have to try this out and see if it works. Expiration is not always a proper solution for things compared to proactive moderation, but the nature of this particular problem is what makes me feel that it’s appropriate here. If we don’t think expiration is healthy then we have to decide on a metric that identifies the junk from the sparkle.
That’s what I’d suggest. Not banning the subject matter as a whole - I don’t see lore as any more bannable than analysis of game mechanics. Yes, lore isn’t a part of gameplay, but story is as much a reason and even a culture within gaming as is mechanics. You have folks who care for the prose in lieu of the numbers as often as we have the opposite, and among us in Arqade we have both camps in healthy counts, vocal and otherwise. The areas that cause squabbles in story are greyer and wider than mechanics, but not to a degree that I feel warrants their abandonment. I pointed at news and design earlier as outside our expertise - I don’t think that lore fits as something we're not the place for.