AJAX has been bad for the web. Letting Javascript make requests without explicit user action & vetting of whatever it's sending is basically the reason the web's so messed up and user-hostile.
Prior to AJAX, sending info was done by loading a "transparent.gif?value1=x&value2=y&value3=z"
It's not technology that has ruined the web. It's greed.
AJAX made that cleaner and broadened its use, but yes, you could already make requests with Javascript that the user didn't want you to or didn't care to make for any purpose of their own.