There is no panacea in cybersecurity. There are certainly better and worse systems out there, but defending against cyber incidents (ranging from intentional attack to accidental breaches) requires a principle derived from the military: defense in depth.
In the 90s, many organizations were unprotected, but those that were protected typically relied on being behind a firewall. This is a static defense; I liken this to the idea of a fortress or castle wall. The story of the fall of Troy is an example of how this system can go wrong. Once the attacking force was within the wall, they had freedom of action across the entire city.
Instead, defense in depth works to create little pockets of detection and resistance. There are still firewalls, access control lists, and the like, but also antivirus software on the endpoints, intrusion detection...
