Email is a decentralized system with no moderation, and it isn't particularly a platform for child pornography or hate speech. (At least, my email box isn't.)

Email is a decentralized system with no moderation, and it isn't particularly a platform for child pornography or hate speech. (At least, my email box isn't.) Imagine a social network where you have an identity based on a key pair. The key pair can rotate every month or so. When you meet someone, and you want to "friend" them on your social network, you scan a copy of their public key straight off their phone via a QR code. Now you can author encrypted and signed messages - you know they're only visible to the people you're interested in talking to, because you have their public keys, and they know the messages came from you, because they're signed with your public key. If your friend Alice introduces you to their from Bob, they might forward you a copy of this Bob's public key, in classic web-of-trust fashion. Alice signs Bob's key, and sends it to you. So long as you trust Alice to not indiscriminately sign keys, you can be pretty sure you're really talking to Bob. You'd easily be able the check the provenance of a key - I have this key that was signed by Alice who claims she got it directly from Bob's phone, and it also signed by Sue, who claims she got it from an email. When I post a message on my "wall", really I'm posting something encrypted with the public keys of everyone I want to share it with. My phone can reach out directly to those phones to pass on the message. If it can't reach all of them, that's ok, because Alice's phone can forward a copy to Bob's phone on my behalf, or we could have some kind of "dead drop" server online where my phone uploads stuff, and your phone checks for it. How does this not devolve into your typical Internet cesspool? Precisely because it's not on Facebook. First, if Bob starts posting crazy ideas about how women should never have gotten the right to vote, I can delete Bob's public key from my phone, and I'll never see anything he ever says, ever again. Second, and maybe more importantly, this social network we've just imagined has no motivation to "drive engagement". It doesn't promote controversial stories to try to get people to click on more ads. In fact, it can't. There's no "service provider" here to profit from it in the first place, and even if there was, it couldn't read the contents of any of these encrypted communications so it wouldn't know which ones are the controversial ones it should try to drive. Twitter and Facebook need moderation mostly because they spend so much time promoting content from fringe crazy people in the first place.