Interesting constraint of "decentralized but offchain" like Bluesky: Everything is signed by secret keys, so either it has to be individually owned or delegated to a trusted intermediary, there is no programmable middle ground.

Whereas onchain, anything that is ownable can also be owned by a collective (or an arbitrary program).

This is very powerful, for example: Posts and block lists and labellers must be owned by an individual, but... wouldn't it be better to have accounts posting owned by teams, or block lists owned by collectives with governance, or labellers owned by verifiable programs, etc?

Can't do that without onchain.

A doodler and computerer. I like permissive/permissionless open source, smart contracts, p2p systems, room-scale VR, and NixOS.

shazow.net

Currently: WhatsABI

Can you?

I was trying to imagine how you'd approach similar functionality with just signatures, and best I could come up with is somekind of MPC or ZK but signature/state aggregation is still an issue and additive signatures require consensus/resistance against peers withholding messages, seems you just slowly reinvent a blockchain?

Yeah onchain provides a collective “right here right now” for coordination to happen. 

But you can do a lot with just signatures.