Antivirus consumes money, staff time, CPU resources, disk I/O, etc.
You can have false positives and false negatives, which can cause even more problems and train people to ignore whatever the antivirus says.
The antivirus can cause security problems as well, things like man in the middle proxies to scan HTTPS traffic, but they "forget" to check the certificates, which handily disables the entire point of HTTPS.
Basically it's makes security worse, and consumes resources that would be better used elsewhere, like say with a whitelist.
You can have false positives and false negatives, which can cause even more problems and train people to ignore whatever the antivirus says.
The antivirus can cause security problems as well, things like man in the middle proxies to scan HTTPS traffic, but they "forget" to check the certificates, which handily disables the entire point of HTTPS.
Basically it's makes security worse, and consumes resources that would be better used elsewhere, like say with a whitelist.