Camouflage is offensive, not defensive. You don't defend your country by hiding it, but you do sneak up when attacking...

Camouflage is absolutely at least as defensive as it is offensive. In the military context - You can defend your country by hiding ie with a nuclear submarine. Camo nets for covering anti aircraft guns, etc. outside of the military context, just look at how camouflage is actually deployed in nature.

Because at one time it was effective, then someone created IR optics and at least for heat generating/storing objects the effectiveness of camo dropped significantly.

Now camo is still effectiveness, say against poor soldiers or one's who had their division leader sell that equipment off to make a little extra income. But you better understand your enemy well, or just putting up camo and then huddling together in a group with no further security will get you killed all at once.

Straw man. Nobody is arguing for ssh on 2222, with root:root for every server.

Also - acquiring / maintaining / training / using good IR equipment consumes far more resources & attention than basic camouflage does. Good troops do something called "field training", where they become quite familiar with how effective cover & camouflage can be. And they've figured out that the stakes on a battlefield are "death", not "deal with server being hacked".

Modern gear reduces your IR signature.

Or the entire classification system. Why should you give the enemy a freebie? Obscurity is just another hurdle/layer that wastes an adversaries precious time.

obscurity is great when you have the ability to strike back. it's less good when you're a server that needs to withstand attacks and can't kill the attackers.

Isn't that because they don't have a more effective alternative? They're forced to rely on the security by obscurity of camo (ignoring the guns).

If you had an indestructable soldier, you could paint them bright pink and have them live stream their position, it wouldn't matter they're indestructable.

Isn't that true for software too though? You cannot ever rely 100% on any tool you use, so if you're serious about actually avoiding penetrations and not just about the academic discussion, you're better off using at least a bit of obscurity on top of your real security system.