I think this is an example of a cargo cult in the original sense: people who didn't understand how and why cargo planes came and went recreating what they saw t

I think this is an example of a cargo cult in the original sense: people who didn't understand how and why cargo planes came and went recreating what they saw the people with the cargo planes do in order to make them appear again after those people had left. A lot of institutional "wisdom" in IT is that you need a virus scanner if you run Windows and because Defender ships with Windows it is therefore part of Windows and not a virus scanner. This isn't really based in anything tangible or empiric, just a learned knowledge that Windows needs anti-virus software and that there is good and bad anti-virus software and that's all you need to understand. Of course AV vendors are very guilty of feeding into this because their income depends on this lack of knowledge and being perceived as doing something vitally important. Realistically the biggest attack vectors these days are (aside from server software vulnerabilities and browser vulnerabilities) someone launching a file they shouldn't have while ignoring every warning message along the way or entering their credentials into a phishing site or telling people things that they shouldn't know. None of these can really be helped with commercial AV software which is why a lot of AV software has moved on to MITM'ing SSL connections to intercept dodgy e-mails or bad links but creating their own potential security issues along the way.