The cases where "content-type" are useful are exactly the ones where
there is no HTTP server, namely "ftp:", "file:" and (in some cases)
"gopher:" URLs.
Whether or not someone could construct a server that would serve the
same files properly tagged is irrelevant.
> Including a hard-wired content-type in a link seems to defeat the purpose of
> the HTTP negotiation algorithm, although, as in overloading the filename, it
> can be of utility when all else fails.
Since FTP servers don't implement the HTTP negotiation algorithm, how
can you "defeat the purpose" of something that isn't there?