Using the notify button came after a lengthy discussion here
as to whether it was quicker/better than the Contact Us
link at the top, and the comments made on the thread following
a spam post. Many got sick of those comments, and the notify
button was the answer, with others refraining from comments
until Anu deleted the post.

By using the Notify button, Anu is only notified once per piece of spam rather than presumably multiple times. If I click the Notify button on a piece of spam posting and nobody else has done so, then I will be able to write a short email to Anu and he will get rid of the offending piece of spam. If, on the other hand, somebody else has already notified Anu about this particular piece of spam, then the would-be notifier is told that somebody else has notified the admin about this piece of spam.

This was explained more than once.

Ceci n'est pas un seing.