Hacker News Reader

Then there are also HTTP/2 and HTTP/3.

That's just HTTP, curl supports 27 other protocols.

HTTP/1.1 - June 1999

It's not like the standard changed since curl was created

That's a tree, but the rest of that comment is the forest.

It (the http rfc) refers to other standards such as for URLs, and those did actually change (to include ipv6 and more internationalisation).