Saying something is a central nervous system depressant is kinda like saying cats are mammals - it’s true, but it won’t tell you what cats eat or what they’ll scratch. You really have to dive into what chemical receptors the drug attaches to to know what it’s going to do to you.

Something that I think the other answers miss is that often military exercises aren’t about training, at least not entirely. Often they’re constructed to test out possible, sometimes wacky scenarios and evaluate performance. Such as - China is invading Taiwan and our Pacific fleet just simultaneously sank, what do we do? Can we still win and if so how?

This is why sometimes you get those sensational news articles about how “a fleet of speedboats destroyed a US warship!” and the like, not realizing that it was a fleet of literally dozens of boats against a single ship with no other support that wasn’t allowed to use half its weapons and in unfavorable position to maneuver, and also it was a rookie captain vs a guy who literally specializes in rapid motorboat assaults or whatever. That’s the kind of stuff that gets concocted for exercises.

Another dimension to this is that intelligence agencies, by their very nature, are very difficult to have proper oversight and regulation of. So it may be in a nation’s best interest to have multiple separate agencies that don’t really compete with each other and have independent chains of command so that one agency doesn’t unilaterally control everything and it’s more difficult to compromise your intelligence network. See how in the US the NSA handles mostly electronic and signals intelligence while the CIA deals more with human agents and spies, and the NRO handles space assets and satellite based intelligence that it provides to those agencies and the many others in the US intel network.