"server" implies that the content being served has the same owner/same scope of control and trust. the sysadmin of an ftp server is the one owning the disk that the ftp server uses; github.com controls the repos that are available on the github site.

i think this whole "mcp security is terribad" thing spawns from the incorrect categorization of the thing as a "server" - if it were instead called a proxy, the rabble would die down.