Email benefits from network effects. The difference is that email is designed to be decentralized and from the beginning had many clients with open protocols. IRC similar. And of course, the web browser itself. DNS.
Back when these were invented, people had many different operating systems and architectures, so the protocol was more important than the client/server. Today, we have about three platforms: web, iOS and Android, meaning you can reach millions of users with software rapidly, rather than the slow way of pushing a protocol. There’s less incentive to have decentralization and there’s money to be made. Protocols require cooperation and therefore move slower. SMS and IRC and email don’t feel modern because they move at glacial pace of cooperation.
I think therefore it’s harder today to push a decentralized, more free protocol than it was when we had more OS/arch diversity. When in a quasi-mono-culture, protocols take a back seat. People don’t ask about it or know what they are. The ratios are flipped: we have basically three OSes and a very large diversity of app/services all incompatible and each locking you in.