Bob, a system administrator at TPNQM SA, concluded one day that a DMZ is not needed if he properly configures the firewall to allow access just to servers/ports, which can have direct internet access,

A DMZ provides valuable network segmentation benefits that are applicable and enhance security even when combined with stateless firewalls.

Relying solely on firewall rules without a DMZ eliminates a critical architectural layer of defense, making the internal network more vulnerable if a directly connected public server is compromised.

A DMZ is always relevant when a company has internet-facing servers because it provides a critical layer of isolation between public services and the internal trusted network, limiting lateral movement even if a public server is compromised. This fundamental security benefit applies regardless of whether a firewall is stateful or stateless.

The value of a DMZ in isolating public-facing services is independent of the firewall's statefulness; it provides a logical separation for enhanced security.