No hexbear was never federated. They started discussing whether to federate and writing moderation rules, sent them to other admins for input, and .world preemptively put hexbear on their defederation list. .world basically said it was ideological differences, they posted all the parts of the draft hexbear rules where they were explaining that hexbear was communist/anarchist and anti-western, and that was just a self-evident reason to preemptively defederate.
The DNC’s actual function is to run the presidential nomination, so right now in a non-presidential year with a Republican president the DNC chair is mostly just a figurehead to hype up the base, and institutional power is with Hakeem Jeffries and the DCCC and Chuck Schumer and the DSCC. That’s why you have a pattern of alternating progressive and centrist DNC chairs. When Democrats lose the presidential election they put in Tom Perez or Ken Martin to keep donations coming and tide them over while they’re out of power, then once there’s a Democratic president they put in Debbie Wasserman Schultz and Jaime Harrison to behead all those who insult Israel.
“DNC” as shorthand for establishment Dems became common back in 2016 when the DNC was very tightly integrated into the Hillary Clinton campaign and was the main conservative power center in the Democratic party. That’s not true all the time but the way power works inside the Democratic party is deliberately swampy and confusing to stop you from putting an easy name to the problem.