> it already only tells you who published the content
No, it tells you the origin of the document. If you are the creator, and you choose to put your content on server X it will tell you "I've got this from server X". Whether that server is a reverse proxy or a shared webhost or a dedicated server in a DC or a raspberry pi running on your desk doesn't matter - it's the designated original that you, the owner of example.org chose.
That's what it always meant, and it changes when you do a redirect, and it shows you the current URL even if there is a canonical header of http-equiv. I can put a reverse proxy on my host and proxy example.com to example.org - the address bar tells you that you're reading example.com, not example.org, as it should, because you're connected to me, not to example.org.
No, it tells you the origin of the document. If you are the creator, and you choose to put your content on server X it will tell you "I've got this from server X". Whether that server is a reverse proxy or a shared webhost or a dedicated server in a DC or a raspberry pi running on your desk doesn't matter - it's the designated original that you, the owner of example.org chose.
That's what it always meant, and it changes when you do a redirect, and it shows you the current URL even if there is a canonical header of http-equiv. I can put a reverse proxy on my host and proxy example.com to example.org - the address bar tells you that you're reading example.com, not example.org, as it should, because you're connected to me, not to example.org.