Maybe it's because I'm idealistic in addition to being old, but I think a lot of this functionality was in fact added for explicit purposes.
A client sends the language header or the list of supported fonts not so that the server can "do whatever they want with this data." There is (or was) a real reason for it when we came up with these standards.
The fact that website providers, or more specifically ad-networks, have chosen to use these for other purposes is breaking that implicit agreement.
(edit) but you're probably right that i'm expecting too much.
A client sends the language header or the list of supported fonts not so that the server can "do whatever they want with this data." There is (or was) a real reason for it when we came up with these standards.
The fact that website providers, or more specifically ad-networks, have chosen to use these for other purposes is breaking that implicit agreement.
(edit) but you're probably right that i'm expecting too much.