In case of abuse this is very handy and allows us to catch malicious users like multiple accounts. Its also useful for staff to see if users have read a staff post.
There also used to be a popular addon that allows you to track a users behavior on the site. This is useful if the staff thinks there is a malicious user active and they want to monitor and track its behavior.
It would be useful if such addon would be available. I would surely buy several licenses.