I can't speak for Julian, but I can talk about my impressions from @boris 's presentation.

He went through a dozen different apps running on the ATProto network that create custom data types and interactions and distribute them through the network. It's all happening on the client side, so these new apps aren't their own PDS servers; they can concentrate on cool client experience and leave the distribution up to the back end.

This is almost exactly parallel to the ActivityPub API. It was cool seeing recipes, check-ins, images, events all being created and managed by server less web clients.

It definitely reenergized me for focusing on the ActivityPub API.