They most-likely used a Reddit Data Request. It’s kind of like Google Takeout if you’ve ever used that. If you’ve already deleted your reddit account it won’t work IIRC. I scrubbed my comments and posts with PowerDeleteSuite a day or two after I submitted the data request, but before I actually revived the data (took 20 days), but all of my comments and posts did show up in the data request. Don’t know if that points to reddit actually keeping that data in their database and just hiding it on the site or not, but either way, if it’s not visible on the site it becomes worthless to them unless they decide to provide that data to someone behind the scenes.
Assuming they’re generally on the same instance ::cough EH cough:: others can just defederate if they want. Those that are harassing and spreading hate speech on mixed servers can be blocked, banned from communities, or the instance in question if egregious enough.
Edit: Am I resurrecting a 3 year old post rn?
Raft by Stephen Baxter. Part of the Xeelee sequence series.
Currently on book 2: Timelike Infinity and I’m liking it quite a bit.