That's the reality of the forum and I still believe it's the best approach for 2 reasons
• The forum is incapable of effectively moderating scams, attempting to handle something you can't effectively do would create lots of loop holes that would be easily exploited and the unsuspecting members who expect to be protected would fall victim.
Consider the 1xbit auction bid, theymos would normally not allow a scam campaign to be posted in banners, but was not aware of it and accepted their bid.
Better to put up warnings for members of possible scams, than giving a faux sense of security.

• Secondly, Bitcoin is a decentralized network and each person involved in it act as their own banks. This forum which is for bitcoin discussions should ideally be designed the same way, you are responsible for your security.
This is probably why a lot of the scam warnings are newbie directed as they are still getting acquainted with how the network/forum works.