Storage doesn’t distribute, though. Every instance needs to save everything. I run my own instance, so the way it works, is that I save everything anyone posts in any community I subscribed to. Permanently, by default.
Bandwidth, sure, mostly. But storage will only grow. And massive amounts of instances will also add issues over time, unlike something like XMPP/Jabber, the fediverse is more of a hubs and spokes model.