I feel like that has a very limited scope of usefulness. Datacenter machines are on 99.9% of the time, and generally speaking, thieves don't go through the trouble of stealing hard drives from datacenters.
In this case the wallet was stolen from the machine after it was rebooted into single user mode. With FDE the machine wouldn't have been usable when it was rebooted so the attack wouldn't have worked.
Did you read the article? The server was rebooted into rescue mode and data has been read directly off the disk. You don't need to steal the drive to execute that.