One of the questions security professionals discuss is what comes at a higher priority in their budget: detection tools or prevention tools.
Ideally, both are needed, unfortunately, resources are not always available and a choice needs to be made. One way to think about it is thinking about your own home security, would you install an alarm without installing locks on the doors? Probably not.
The same should be applied with your IT Crown Jewels, especially with the sophistication of attacks allegedly seen on Yandex by intelligence agencies, the prevention tools companies were called in for a reason, their tools didn't detect the attack and if the doors didn't have locks then it's a "free for all" attack surface.
Protection of Crown Jewels against the Crown Jewels of malware would be the safe bet, detection would be nice and after the fact of the breach.
‘CROWN JEWEL’ Security experts say attributing cyberattacks can be difficult because of obfuscation methods used by hackers.