That's how outbox works yeah.
You connect to others outbox relays to grab their notes. You connect to their inbox to send them replies, zaps, reactions, etc.
For other users it's vice versa on their end, they read from your outbox, and send to your inbox.
It solves the issue of needing common relays to communicate, and makes Nostr actually decentralized and resistant to censorship, rather than relying on a few relays that can be taken down or censored.
Also was 1100 the first number, or the second? In my example 318 is the actual number I'm connected to, out of a possible maximum of 691.