Nostr and relays protocol
Is like
HAM radio and repeater technology
Both decentralized
Run your own relay and repeater
Discussion
Another close analogy:
Many ham radios have a built-in repeater called crossband repeat allowing setup and use as a repeater to be a simply trivial matter. You dont have to buy more hardware and you dont have to know much about repeaters to relay messages other than a couple of frequencies to use and turn it on.
Nostr relays are becomming that easy to use. There may already be clients with built-in relays, but if not there will be soon.