I it is not that we don't need it but it is finally obvious that there is no reliable way to detect harmful software. All we are left with is putting each and every application in sandbox, unable to interact with any other software or user data. It is just very hard to make that user friendly and acceptable for average Joe.
No, not like condoms. If STDs became blockable with common sense and condoms started shipping with perforations and prickles on the inside then yes, but that's not the case is it.
http://decentsecurity.com/about/ (This entire website)
https://www.microsoft.com/emet (for Windows)
https://paragonie.com/blog/2015/06/guide-securing-your-busin... (basic web security advice for non-technical people)
You don't need AntiVirus.