540
Phishing
(feddit.org)
If a single click on a phishing email can ruin the entire company, the blame doesn't lie with that individual.
While I somewhat agree, there are things even the best spam filters can't filter and Zero-Day-CVEs that Sys-Admins can't fix.
On the other hand, the company should be confident in their backups, which in most cases should allow for a continuation of their activities.
You're forgetting all the hardening in the middle to prevent the privilege escalation that would enable mass deployment of ransomware.