Of course, a protocol by itself isn't very useful. You need services using it and systems implementing and supporting it, which do cost money and require some kind of resourcing model...
Is Morse code less useful because of the lack of viable Morse code service providers?
You can use Morse code without any service providers whatsoever! Though using it to send messages solely to yourself might not be the best of all possible uses, it's absolutely a viable use.
Similarly, you could implement SMTP for yourself on paper. It might not be quite what was intended or maximally useful, but it's certainly a use. Some people might opine that it's far more useful with services implementing it widely and making its benefits available to many. I can't say they're being wildly unreasonable.
Cheap cop-out. "some webmail provider" is what runs 99.999% of email. The people who run their own email, or run off hobby email servers, are insignificant.
You can't turn a blind eye to where the majority of users are going to be if you're implementing anything that actually needs traction in order to be successful.
Federated social networks are like email: each instance is like the "webmail provider" you can pick and chose and some of them even come with their own clients and bells and whisltes.
Protocol doesn't need a business plan.
How is this so hard to understand?
Products in developed countries is much more valuable than products in third world countries.
I don't agree. What is the business plan of email (by which I mean SMTP, not some webmail provider)?