-- ps
So the question is whether it is possible to have effective solutions in that design space. Email in fact fits these design parameters: end users can use PGP and PKI to have private and authenticated communication, but as Moxie knows far better than me, it hasn't happened because now we have shifted the burden of running 'something' back to the end user again, who is now responsible for participating in a 'decentralized trust' system.
It appears the problem is reducible to (and thus is fundamentally about) identity and associated attributes of an identity.
So what we really need is a decentralized identity infrastructure with 'last mile' interfaces to your physical political jurisdiction for those who want "legal" attribution for fully decentralized interactions (possibly built on centralized infrastructure). All other "Web3" systems can be built on top of these.