@feditips The difficulty with having the server backfill is that now it has to store all of the old posts from an account that no one followed before, just because one user of that server wants to see them (though that might be fine for a single user instance, the cost could be high otherwise). It seems that instead, we could design apps, or the web interface, to fetch the old posts directly from the account's instance instead of requiring that they move to the server first.