The article is out-of-date. Many Plus discounts are only good for a week, and the free games vary from month to month. That number changes every week, and is only good for a week. Sony does not calculate that on an ongoing basis because it is meaningless. You would have to have been a Plus subscriber from the first month in order to have access to everything that had been offered, and because Plus subscribers don't get a choice about what is offered free or discounted, there is no reason to think that any sane person would actually ever buy all of the content that was offered; or did not own some of it already before it was offered in Plus.
The vast majority of the free games offered to Plus subscribers are well after their release date on PSN, and have already sold most of the copies that they ever will. Anyone that really wanted to play the games probably already purchased them. The others tend to be titles that did not sell well to begin with, suggesting that most of the people that download them for free would never have paid for them anyway. Sony knows what it is doing with Plus. Plus is a good deal for many gamers for the free content alone, but Sony isn't giving away the store. It is like those sales circulars that advertise "Thousands of dollars in savings!". To save thousands of dollars, you would have to buy tens of thousands of dollars worth of things you don't want. Nobody does that. It was just a marketing gimmick that Plus really does not need anymore, which is probably why you are having trouble finding it.