Being a Mac user myself I can agree that a lot of bickering does go on when the topic of "virus" shows up regarding Macs. While true that there's none in the wild, knowing what kind of malicous software is out there is good information. However Mac users generally don't like to admit that their loved systems have a weakness to other things and like to have an edge over Windows systems stating "well Windows is weak to viruses". Nearly everyone with current knowledge knows that viruses aren't very common and quite frankly not that important to bicker over anymore.
Like the article in the link covers, it's more imporant to know the mode of transport the malware uses gets onto each machine and identify what it does and how we need to deal with it. Mac users can be so hard headed sometimes. I always bring up the point about how it's less important to argue about whether something is technically a virus rather than it is about OSX is not bombproof to other forms of malware.