There are many, many RFC collections. Including many that predate the IETF. Some even predate computers.

But they were in different domains. Here, we have a strong clash because Rust is positioning itself as secure system and internet language and computer and internet standard are already defined by RFC-s. So, it may be not uncommon, when someone would tell about Rust mechanisms, defined by particular RFC in context of handling particular protocol, defined by... well... RFC too. But not by rust-one.

Not so smart, when we realize, that one of aspects of secure and reliable system is elimination of ambiguities.