> I can't speak to why it was originally defined, but since the Referer [sic] header has existed for decade
I can remember my Dad getting a mail from someone he linked to that was about to move his website and politely contacted his neighbors on the internet to allow them to update their links.
It can still be useful for that kind of thing. When I notice an unexpected spike of traffic on one of our sites I'll often look at our analytics to see where it came from and then potentially drop in there to answer comments and such. Not to say that's worth the privacy trade-off though, unfortunately.
I can remember my Dad getting a mail from someone he linked to that was about to move his website and politely contacted his neighbors on the internet to allow them to update their links.
Very useful at that time.