Just been reading about Scuttlebutt, a social networking app that doesn't even rely on having the Internet. Seems you could even exchange data with USB drives. Okay, so it would be slow, but nobody could shut it down.
One of the cool things about steemit is that it's hard to shut down. We don't rely on having the web site as there are alternatives. You just have to compromise somewhere if you want speed. The key to all such systems is cryptography as that allows you to prove who you are and what you wrote.
There are some clever people out there working on new ideas.