Ok, disclaimer first: I've previously worked at Kaspersky Lab (incident response division). Now, I want to say that many of the incidents that we have investigated, would have been prevented by anti-virus software (in many cases AV software was deliberately disabled by user). And I'm talking about incidents that resulted in million-dollar thefts - not just cases of some user getting cryptolocker on their home compute…
Any AV software is better than having none but that's not the point of the article. It specifically recommends Microsoft's AV and to stay clear of all the others. I'm sure it's hard on all the AV vendors out there but with Microsoft Essentials and Windows Defender I don't see the need for a third party AV.
I mean, I get the attitude of "common sense is best" - users who know what they're doing will most likely avoid infection if they're not extremely unlucky.
However, I still find it amazing that while people pay a lot more for insurance against less likely events, but the thought of paying few cents/day for an added layer of security for their machine (the same machine that in many cases stores a lot of personally and/or financially valuable information) riles them up.
When you're online you're constantly exposed to threats, and while it's easy enough to ignore spam email and unsolicited messages on Skype and FB, a momentary lapse of reduced attention could get you infected.
For example, here are some ransomware infection stats: https://blog.barkly.com/ransomware-statistics-2016
/rant