(6/?)
Firstly, because of the protocol physics of how ATProto works, most of the people with BS accounts are irretrievably stuck on the company's service. As @cwebber pointed out in her analysis, BS accounts aren't really that portable in practice;
https://dustycloud.org/blog/how-decentralized-is-bluesky/
Yes, setting up clones of the big machines of the BS service would allow people to interact with BS accounts without using any other part of BS. But there's a simpler way to do that, which brings me to point 2.