I agree, and the blurry image weight approximately 678KB (~88% of the size in bytes of the whole page). I'm sure there are less costly ways to create a fake page or to show that you are not allowed to view the page.

Yes, this is the biggest issue the are facing right now. However, since they launched 24 hours ago, there is no ad revenue to kill yet.

I guess the current invitation system is temporary and will be updated to let public content available to anyone.