Still, it’s an interesting space, I think.
Still, it’s an interesting space, I think.
Email was never a binary protocol. Notoriously so, it's why MIME types and MIME encodings get so complicated.
Most of the "old internet" protocols (email, FTP, even HTTP itself) were bootstrapped on top of built-mostly-for-plaintext Telnet. HTTP as the new telnet has a bunch of improvements when it comes to binary data, request/response-based data flows, and some other considerations. HTTP/3 is even inherently a binary protocol, it's lack of "telnet-compatibility" one of the concerns about switching the majority of the web to it.
vCard/vCal/iCard/iCal were also deeply "plaintext formats". JSON is an improvement because it is more structured, even more efficient, than those predecessors. JSON may not look efficient, but it compresses extremely well and can be quite efficient in gzip and Brotli streams.
I feel like "JSON over HTTP" is a subtle improvement over "custom text formats over telnet", even if it doesn't sound like "binary protocol efficiency" at first glance. Especially as HTTP/3 pushes HTTP more efficient and more "binary", and arguably "more fundamental/basic" with HTTP/3 even taking over more roles in the TCP/UDP layer of the internet stack. (Telnet would never try to replace TCP.) HTTP isn't the worst bootstrap layer the internet could use to build new protocols and apps on top of. Sure, it would be neat to see more variety and experiments outside of the HTTP stack, too, but HTTP is too useful at this point not to build a bunch of things on top of it instead of as their own from-scratch protocol.
That's just not true. Telnet and SMTP are built on top of TCP. They live on the same layer. They were originally both protocols that transmitted data with printable ascii, hence why they look similar. There are many other protocols like Telnet and SMTP that worked like that, auch as nntp, irc, and yes, even http.