The CTO @pfrazee had a lovely New Year's Eve post that talks about Atmospheric Computing and specifically raising the cold start problem and addressing how atproto tackles it. https://www.pfrazee.com/blog/atmospheric-computing

Tangled here is a great example. An existing user base of a social network was able to rapidly join and start using a new app, a git forge, to share repos and collaborate. PRs and comments show up like any other record on the network.

As for how the network works: atproto tackles the cold start problem by layering architectural concerns. Each person is their own server ("personal data server" aka PDS). But aggregation layers ("relays") collect all PDS activity they can find and relay it to consumers. Then applications such as Bluesky or Tangled ("appviews") can be built by reading records of interest (of the right "lexicon" type) from the relays. Each person owns their data, relays make all data available, appviews distill out user experiences appropriate to the records they cover.