You are right, this is not necessary, and we stopped recording this information a while ago. Sending this information should be an option that users can turn on or off at their leisure, if it happens at all. Our aim is to provide our users as much privacy, and control over their privacy, as we can, and this old design choice does not fit that aim.

The Firefox addon has never sent that information, and (though not recorded anyway) we'll be removing it from the Chrome extension and updating our privacy policy shortly.