Linux

This isn't helpful, nor true. As technology grows, so do attack vectors, so do malware devs, so do vulnerable softwares, so do cloud servers and SaaS and android and steamos and IoT making linux a juicier target.

Two truths of "common sense" is that it's rarely actually common nor does it make sense to anyone not already In The Know. The "Sense" that is actually common is often wrong.

If by "Common sense antivirus" you mean "don't download and run the Hot Singles Finder ELF from a xxxNerdsDickedDown.com ad," that kind of common sense simply isn't enough to ensure avoiding infection anymore; if you mean "use a firewall, and don't install/run anything without checking signatures/checksums, and prefer sandboxing, and also check for exploits of application management programs like Steam or Google Play that are theoretically supposed to be checking signatures/checksums for you, and use a password manager, and don't click on the links in email, and check the headers to ensure it's actually fron who it says it's from, and..." then you're far outside the realm of "common."

If your kneejerk response is "that's just being overly paranoid," congrats, you have become a User: you are the type of person who needs something to automate checking for malware/exploits so you don't get yourself botnet'd.