To be similarly pedantic: Ctrl+C is a hotkey that sends the corresponding ASCII code / codepoint to signal something, it is not an ASCII code itself.

You could have the same character be sent by using Ctrl+Q (if you were to remap it), and not break compatibility with other processes while doing so: the codepoint being sent would be the same. From a technological perspective there is nothing special about the key combination Ctrl+C specifically, but altering this behavior in a terminal absolutely wreak havoc on the muscle memory of terminal users, and altering it’s behavior in a text editor on everyone else’s.

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)