This is true. Sorry if I sound like I'm having a Victor Meldrew moment about this. As others have pointed out, it's not the end of the world.
That said, we do have this statement towards the top of the main forum page:
"Please note that, at busy periods, you may have to be a Registered or Full Member in order to view the main forum."
Which would lead one to believe that there is a configuration switch somewhere that could be flicked. I'd be inclined to restrict it to "Full members only" at really busy times, just to see how it panned out.