Aren't UTF-8/16/etc encodings and not charsets (the charset is UTF)? Also, in RFC 9110. Section 8.3.2. "In the fields defined by this document, charset names appear either in parameters (Content-Type), or, for Accept-Encoding, in the form of a plain token." Are they effectively synonyms?
I know that content-encoding is usually used for compression but it seems like content-encoding should accept stuff like Base64 or UTF-8. For example, how do we communicate on-band that data is encoded in Base64?
There are other explanations for this question but they go into conventions and not into reasons.
