I certainly hope nobody said it, because exploits already existed back then. However, active exploits in the wild, actually taking over Macs, do not exist yet. Maybe some day...
As I stated then...security by obscurity is not real security.
Then it's good that Macs don't rely on it.
But their users do... most I know don't even run AV protection.
Once again...security by obscurity is no security. Reason they don't exist is because there's not enough bang for the buck for the hackers. Oh and btw, they do exist...ever heard of Leap-A or Oompa-A. Now what's your defense.