The fediverse is probably the best answer you're gonna find to digital feudalism that is compatible~ish with the real world. Which is to say; it theoretically divides the risk that any single castle and king could hijack the entire process up into many smaller castles, meaning that if a king turns hostile, you can go somewhere else with relatively little friction.

The reality is that if you truly want to get rid of digital castles and kings, you're essentially going to have to operate a distributed digital firehose (cynically: digital sewage pipe) that anyone can submit to with no preconditions whatsoever. For many reasons (first one that jumps to mind: spam, second reason: illegal shit, third reason: trolls) most people don't want to operate something like that, and that's before the law gets involved.

Pet projects exist of course, but pretty much zero of them are made to scale up against the idea of truly nuking kingdoms; the closest to a realization of this sort of network is something similar to TORs peer2peer, and you can consider pretty much all legal risks of running a TOR exit node for a service like this.