But they aren't. Nobody is suggesting to anybody to use NONE as the algorithm.
https://www.rfc-editor.org/rfc/rfc7518.txt
Still, my point about it missing from RFC7115 stands.
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The standard says you should support NONE as the algorithm and that you should use the algorithm the client sends you, all the while completely failing to mention the issues with that, both in its Security Considerations section (which mentions even more "obvious" things like "use keys with high entropy") and in the description of the algorithm to decode a token (which initial implementers probably relied upon to get to a "correct" implementation). Sorry, that is a failure of the spec as well in my book.
If you spec something with risks, at least mark the critical parts clearly with "point away from foot".
A better standard IMHO would have suggested the API for the decode functions, making it clear that the algorithm used should be whiteli
If you issue tokens with none, then you will have to accept them when clients send them back. This is obviously a very bad idea, but that's all th spec says. If the issuer chooses to be insecure, that is a valid choice.
If you issue tokens with a specific algo, and clients send them back with a different or none header, you know they have been forged.
The spec allows issuers to decide whether to use none, it doesn't say you must trust none tokens if you know you didn't issue them.
A standard promoted as "the standard for secure tokens" should not aim for "You can use the pieces to build a correctly behaving system" or "the spec allows secure implementations", it should aim for "if you use this and follow some spelled-out basic rules you get fool-proof secure tokens" and make wrong usage as hard has possible.