Nost is in essence is a communication protocol rather than a network. It's relatively unique feature is the private-public key cryptography it uses for signing & verifying communication events.

You are currently experiencing a social media application of the protocol, but Nostr is simply communicating events.

I don't know who you are but I know that this note was signed by the controller of nostr:nprofile1qqsglwezznkx0a07qr0e2vfr53lu0fhv8vlt55ceernu343uejkl4asppemhxue69uhkummn9ekx7mp0v0rp86
My client has verified this. 

This npub is unique to the private key that you control & I can quickly & easily verify that any of your future notes also come from your private key.

Blockchains are useful when the sequence of recorded events is critical. I cannot verify the time in this note but I can assume that it's accurate, since it's plausible & doesn't really matter. This is partially why the Bitcoin blockchain is often called The Timechain. 

Assume Alphacorp uses npub123 to publish an event to a specific relay that "100 widgets are required from npub456". Npub456 can sign a note  that the order was received, picked, dispatched, etc. Alphacorp knows that these messages originated from Omegacorp because they know that Omegacorp is npub456 & the events were cryptographically signed.  Software clients can record when events were first seen as well as the time declared in the event if sequencing/timing is important.