So, something like AO3's viewing history or YouTube's watch history.
Did you check your browser history as well?
Somewhat related:
Mark series as read even when they're not followed and
mark read even without following. Note that there seems to have been some scaling troubles with recording chapter read history, so the website was changed to only track chapter reads when the manga status is set to "reading" or "re-reading". However, your suggestion would only track by manga instead of by chapter, so that wouldn't be as bad.
Obviously, if it gets implemented, there needs to be an option to turn it off :3