Also, is it really true that a state actor could not effectively block email? Or for that matter all encrypted email? They are, after all, blocking web pages. It seems to me (as a lay man observer) that at the state actor level the Internet is relying on centralized resources already, maybe that's why decentralization seems intuitively less important to me. This is not to disagree with your points.
It's more that a private actor can exclude you from any network. Maybe WhatsApp blacklist you for "abuse". Maybe they're right. But even if you kill someone you're allowed to use the telephone network, and send or receive letters.
As long as the message silos aren't regulated as utilities, decentralised systems give us more of the freedoms.
It's pretty easy to run a separate dns system - you can even blend your own private "authorities" dns for new tlds with fall back to the centralised root servers.
That's a fair point actually. Does the fact that signal is open source and based on phone numbers change that though? Seems that as long as you have access to the phone network you have access to the signal network...
They can block any traffic in/out of their network. But e.g. it's possible to use email on a LAN (or a wireless mesh network) entirely disconnected from the Internet.
