Er... what?
By "raw octet stream", I meant that the client should upload a file named X made of opaque bytes 0xABCD, as a file named X made of opaque bytes 0xABCD; rather than assuming a higher-level intent on the server's part to acquire some abstract document, where the client would be able to better serve that request by transforming its file to a different file-format.
I didn't mean that e.g. the client should avoid using Transfer-Encoding compression during the HTTP POST request, or anything like that. (That is, after all, a fact about the wire representation of the request; it doesn't affect the file received on the server end.)
Or, to put that another way, an <input type="file"> with no `accept`, is to the client, as `Cache-Control: no-transform` is to the server: an expressed desire to get some specific data that exists the other end sent over "as it is", rather than to get something customized to the peer's needs.