I think that "Don't run several pieces of years-old third-party software with multiple publicly-known code execution vulnerabilities as root/SYSTEM on possibly

I think that "Don't run several pieces of years-old third-party software with multiple publicly-known code execution vulnerabilities as root/SYSTEM on possibly malicious input" is a bare minimum requirement to demand of a piece of software whose entire purpose is to analyze untrusted data to prevent malicious code from executing on our machines. If it's unrealistic to ask that of AV software, then I'm not sure how this works out to be an argument for AV.