NDAs are the biggest crock of shit ever and should be made universally null and void, yes, even in cases where they're valid. What the fuck is the point of having freedom of speech if someone can just coerce/threaten/force you to into signing it away?
I think there is an argument to keep them for things like products in development phases to stop people from blabbing to possible competitors, but this particular situation is bullshit.
Technically a Page 13 in a government/military setting is an NDA. Now in your ideal world, sure, you'd never need to keep secrets, but in the real world, you probably don't want a potential invader to know your exact defense systems, capabilities, guard locations and the best and least guarded places to come in and out.
Even assuming a completely peaceful world, you probably don't want to be sharing the passwords to critical infrastructure or the private medical information of people on a hospital database.
Not just the US military - any military. Plus the designs for nuclear weapons, bioweapons and chemical weapons becoming public knowledge. How would you like some plague and radiation for breakfast, white phosphorus for lunch, and then nerve gas for dinner?
I think white phosphorus manufacturing is pretty open knowledge or atleast the most baic form of manufacturing, its just that its so volatile that generally speaking its not worth it.
Same with nerve agents, ya basically need it on an industrial scale to be effective. Remember that cult in Japan who gassed the subway, they also did the same thing with trucks its just that it diluted and was blown away that only a handful of people died and most got a bad headache at worst.