Least privilege security myth

Today, the Linux Hater made my day by busting one more Linux Security myth:

[On Linux,] users created on the system are not administrators, so system-wide security vulnerabilities introduced through the user and highly improbable. Antivirus software, as well as software needed to remove malware, spyware, etc. is not needed, as the security design behind the operating system does not let this software grow beyond the user’s home directory.

Thank God! My rogue script only deleted my home directory! I'm so happy it spared my /usr/lib! I just have to reinstall Ubuntu to get my home directory back, right?