I searched for instances on Lemmy. There are 4 but they’re unmoderated or appear to be moderated by a bot.
Yeah, it’s seen as one of the important resources worth saving from Reddit, so there are efforts to preserve the information. So !historiansanswered is using a bot to extract it. The majority of lemmit.online is bot-driven and I blocked it as it can really stuff up your feed.
It seems likely that a similar human-moderated community hasn’t been started because it is such a big deal and would require not just a critical mass of people (especially historians) but also a strong mod team (with solid mod tools) to keep the signal to noise ratio up or, I’d imagine, it could get messy, quickly.
That said, a bit of messiness isn’t necessarily a big deal while you are building a community and,.in this case, it wouldn’t be dangerous compared to communities focused on health or legal questions. So if there isn’t an equivalent on here, get it started and we’ll see how it goes.