> As of 22 June 2005, Gmail's canonical URI changed from http://gmail.google.com/gmail/ to http://mail.google.com/mail/.
As you can see from your own source, the canonical URL has always been under google.com, not under gmail.com.
Edit: the parent post was originally linking to https://en.wikipedia.org/wiki/History_of_Gmail, before being edited
Therefore, gmail.google.com could track cookies and activity via google.com.
This has been fixed since then, so I think the memory of the internet is short and wouldn't understand how bad this was in retrospect.
(my previous edits: Yep, I didn't want to drag this out. My memory was off on something.)
> As of 22 June 2005, Gmail's canonical URI changed from http://gmail.google.com/gmail/ to http://mail.google.com/mail/.
As you can see from your own source, the canonical URL has always been under google.com, not under gmail.com.
Edit: the parent post was originally linking to https://en.wikipedia.org/wiki/History_of_Gmail, before being edited