Maybe they have the wrong concept?
The current operating concept is that to be a good defender, you need to be a good attacker. While that sounds right, not sure there is any evidence it is right.
The role of defender is actually a lot more structured and a lot more disciplined than the role of an attacker and there is little or no evidence that taking time to be trained up to do attack (as opposed to understanding how attacks are done/happen) takes away to much time from learning to configure networks, secure applications, monitor for anomalous behavior, etc...
There are so many ways to attack a network that it is very unlikely that anyone can know them all and, frankly, the attacker only needs one success while the defender can stop thousands of attacks but fails if there is one discovered vulnerability that is exploited. Spending a lot of time learning exotic attack methods won't help if the attacks are coming in on mundane paths you didn't think were important.