There are definitely valid uses of blockchain tech but requiring it as central part of the architecture is a recipe for (re)centralization because eventually it will always grow beyond home-computer scale.
I'm pretty sure I would say that the above is not how things work in human society. Limited trust, fiat currency, and regular disagreements is the norm.
If a system forces all users to be part of some large, Borg-like, distributed hash table, or ledger, then by my definition it's not "fully decentralized".
Today, people can, in theory, choose from among billions of peers to form these small groups. And the groups can if they so choose connect with each other, via a network of networks.
This internet "connects billions of people". True. But your company's LAN probably does not connect that many.
If a user started creating numerous fake identities on the LAN, then it's likely she would be detected.
Is it possible to create distributed "LANs" over the internet? (rhetorical question)
Another commenter questioned why a distributed Web needs "lack of trust".
People in small groups can and do trust each other. No computers are needed to make this happen.