Now compare this to git-ssb. Each "user" is simply an ssb feed, and repositories are tied to one specific feed.
Repositories in #git-ssb are not tied to a particular feed, since almost two years ago: %SXGbKel.... Recently I was considering changing it back to one feed per repo, which prompted some replies, somewhat summarizing the state of things: %SxFKMme... ; having an organization contain the identity of a repo as you described would be another approach.
More SSB applications could make use of tangles to help with replication / data discovery. vote
("dig") messages could reference other vote
messages. Messages in a channel could reference other messages in that channel. about
messages reference previous about
messages; contact
messages could reference other relevant contact
messages, This could help us discover, share and interact with messages from outside our friend group without having to already replicate their feeds.