> Let me ask you this, is it possible for me to connect to a PDS directly, right now, via the bluesky app?

Well, yes, that's what you do when you log in. If you open devtools you'll see that the app is communicating with your PDS.

> So are relays really just an optimization or an integral part of how ATProtocol is supposed to work?

I think the issue here is that you're mentally slicing the stack in a different way that atproto does. You expect each node the be a full instance of the application, and that the network gets partitioned by a bunch of applications exchanging peerwise.

A better mental model of atproto is that it's a network of cross-org microservices. https://atproto.com/articles/atproto-for-distsys-engineers gives a decent intuition about it.