If a user doesn't want to send the referrer when there is no referrer, no referrer should be sent. This then allows sites to distinguish between direct traffic from users that don't block referrers and traffic with blocked referrers. I wouldn't expect this to be a significant concern, because the volume of actual direct traffic is not very large.
When analyzing traffic sources for your site, you could use this to remove noise created by privacy conscious users. For example, if you wish to evaluate the efficiency of a magazine add, today you can't distinguish between ad conversions and privacy conscious users.
It'll take a while for clients to be compliant, if they'll ever be, though.
> if you wish to evaluate the efficiency of a magazine ad
Sorry I still don't get it. No referrer or about:blank are both "noise" in such case, I still don't see how the distinction is useful to the server to evaluate efficiency of a particular ad.
