Where's the circularity? This is the claim: you can't claim that a nonexistent thing is proprietary. Rust and Go do not (to my knowledge) have any sort of standard other than the living standard of the reference implementation, which is itself not proprietary. Anybody is welcome to copy or modify that living standard, per the terms of the permissive license.
This is the overwhelmingly common state of affairs for programming languages: Python, PHP, Go, Rust, etc. do not have formal standards in the sense of C, but instead of a living standard in the form of their reference implementation. The reference implementation is permissively licensed, so the "standard," insofar as it can be said to exist, is also permissively licensed.
Edit: Again: this is just not what the definition of "proprietary" is, in the context of open source. There is a legitimate grievance that you're expressing about software standards and implementation diversity, but it has absolutely no bearing on whether the reference implementation is proprietary or not.
By analogy: I, an open source developer, create a new file format $FOO and release my reference implementation of a $FOO parser under a permissive software license. Am I somehow compelled to spend time writing a formal specification of $FOO to make it non-proprietary? It might be nice for me to do, and nothing stops anybody else from converting my living standard into a formal one, but I am absolutely not compelled to do it.
This is the overwhelmingly common state of affairs for programming languages: Python, PHP, Go, Rust, etc. do not have formal standards in the sense of C, but instead of a living standard in the form of their reference implementation. The reference implementation is permissively licensed, so the "standard," insofar as it can be said to exist, is also permissively licensed.
Edit: Again: this is just not what the definition of "proprietary" is, in the context of open source. There is a legitimate grievance that you're expressing about software standards and implementation diversity, but it has absolutely no bearing on whether the reference implementation is proprietary or not.
By analogy: I, an open source developer, create a new file format $FOO and release my reference implementation of a $FOO parser under a permissive software license. Am I somehow compelled to spend time writing a formal specification of $FOO to make it non-proprietary? It might be nice for me to do, and nothing stops anybody else from converting my living standard into a formal one, but I am absolutely not compelled to do it.