I was checking out my computer analysis limits on the membership page and something caught my eye.

Private Premium Forums

Private Premium Forums

Premium Members get access to private forums which help to filter out some potential immaturity in the public forums. The GOLD forum is for all Premium Members, while the PLATINUM forum is for Platinum/Diamond members only.

Now, I've never seen these on the site or is this forum "Premium Members" the same as the GOLD and PLATINUM forums listed? Or possibly it was a feature considered and discarded as unnecessary but still listed for advertising purposes?

Yes, the "Premium Members" forum is for all premium membership levels including Gold, Platinum, and Diamond. This will be fixed on the membership page.