Yeah, but Bukkit is ancient - so ancient, upstreaming is basically impossible and even discouraged because it would break compatibility with the few people who

Yeah, but Bukkit is ancient - so ancient, upstreaming is basically impossible and even discouraged because it would break compatibility with the few people who still need it. It's really only maintained as a reference architecture by Spigot because it helps with initial Minecraft release reverse-engineering. Spigot, meanwhile, is run by one developer who only posts his code within a few weeks of a Minecraft launch after working on it completely privately. Paper has examined taking over that role, but has decided against it for the time being until they are ready to fully take on that job because... it's not an easy job and he's basically mastered it (Paper would be much slower if they were doing it themselves for the first few releases). Also he runs the plugin repository and Paper isn't ready to launch their own yet. Also, Spigot and Bukkit have this ancient API that not many plugins use, but a few do... and it'd be nice to not break them. So Paper is the first remotely reasonable downstream with a big open-source community for it, which then makes it more like... one fork. And even though Paper is technically reliant on Spigot (and Spigot on Bukkit), Paper can really cut them off whenever convenient. And there's a good reason to make Folia a fork - the way it works under the hood is very different than a traditional Minecraft server, and it basically breaks all the Spigot and Paper and Bukkit plugin compatibility.