They don't need to run their own node. A client can be hosted by an operator – you can access it similar to how you access Twitter, except that it's just a client, you can switch to another client whenever you wish. 

maciek

nostr

Nostr decentralized social media -- "wow, this can work!" 🧵

cryptocoin

I like the idea.

So you need to run your own client/node. Is there a lot of data growing over time?

I don't think many people will use it if they need to run a node though. But if it works in a bunch of social media platforms I guess it doesn't matter as the Normie's gonna norm 