but scaling is hard, and distributed tech is hugely inefficient
How is it inefficient for a chat app? If anything, a distributed architecture is the ideal for this use case. It's only potentially a problem if you need to have huge group chats, which is definitely not the common use case for a chat app, but even then I think Delta Chat's optimized relays can handle that.
see how it goes, and when the solution has scaled in the real world to what it’s competing against then you can feel superior as the one that had the vision to see it
Delta chat uses existing email infrastructure, which has already proven its ability to scale. Nigerian princes probably send more emails per hour than the entire global Signal network.
Idk what to say to this. Is it true? I don't know, and you probably don't either. That's a weird way to look at it and I doubt anyone has measured the power costs of the global email network.
It's also useless for decision-making. What matters is a question like "how much would it cost me to host a server and contribute to the network?". Even if the total global cost is billions of dollars, the network will continue to grow because nobody has to pay all of it.