Crap article, crap title, written by someone who can't distinguish between "of questionable value and utility" and "malware". Nowhere in the article does it state why MacKeeper is malware. In fact, the last linked article at the bottom ("Please beware") specifically says that MacKeeper is not malware. MacKeeper might be a waste of money, it might use questionable advertising (pop-ups, and typically on less savory sites), but malware it is not.
Additionally, the information on AV and how it works is sloppy. This is already covered well by other comments here, so I won't belabor it.
>Nowhere in the article does it state why MacKeeper is malware.
I don't care about any such fine distinction. It's an annoying crapware that pops out of adds that pretend it's a system message for my Mac and that I'll be in trouble if I don't use it.
> Then they must find a copy of the virus, examine it and add it to the list of virus definitions used by their software.
Strictly speaking, this isn't true. The major AV companies use file behaviours to try to stop viruses as a first line of defense, something like "if a file is an executable and it tries to run some manner of encryption on files in the My Documents folder, its likelihood of being a virus is high". AV companies use file checksums as a last-ditch effort because most viruses out there are polymorphic (they have some unused data section at the end that randomly changes, which busts checksum detection).
A lot of AV companies also offer virus cleanup services, so if you do happen to get hit by a virus that snuck by, they can help reduce the damage.
Nobody's saying "use AV and you don't have to ever worry again". AV is just another piece of the defense puzzle, along with user vigilance (don't click that link in that email from "eBay"), operating system restrictions, network restrictions (to help prevent data egress), and so on.
I read through this quickly and completely missed the part where MacKeeper is Malware. Malware is a strong word for something that just has questionable utility.
Can't comment on MacKeeper itself, but i feel this is a really stupid advice...
You don't need an antivirus because virus definitions are slow to update? Fine, but what about old virus? Am I protected by magic?
Also, I feel like the increase in OSX popularity will result in an increase in malware for it, so I'm not sure for how long "OSX is virus-free" will be valid
You protect yourself by not clicking on executables you don't trust (or running them in a VM). Its not magic, and its better than a false sense of security from anti-virus which is easily bypassed / poisoned (for example, even a clean bitcoin client will set off AV alarms).
Additionally, the information on AV and how it works is sloppy. This is already covered well by other comments here, so I won't belabor it.