The key issue is that the request is to change behavior in one place (browser) to match that of a rare case (terminal), causing a mismatch with the frequent case (office suites, mail programs, …). The terminal is the odd one out, not the browser, and ought be the one to change the default for the reason you provide.

In practice, a terminal is a special case and not just a text input window, and current convention is that Ctrl + C aborts / cancels.

(You could of course have a duplicate hotkey, but now you are inconsistent w.r.t. other browsers, and there will be someone else who will be annoyed by the difference)