Expecting everybody to run a relay isn't unrealistic if it's automatic and bundled with their nostr app of choice and requires no additional administrative overhead. Fully P2P networks have a long history of being functional and working. There is zero reason we need to centralize around relays. An android phone can easily store a million text notes. Maybe for larger file storage we need something else, but for 90% of what nostr currently does? An android phone could be a relay.