If the breadcrumbs are realistic then you will end up having employees mistake them for real data, and the employees being mistaken for an attack, no?

If the decoys are realistic then they will have realistic behaviour, for instance, doing an auto update. Now, let's say I'm a malicious actor on the network, and I fake the auto-update server so the patches downloaded are backdoored. Its very hard to detect this attack. Any network has a lot of broadcast traffic between all the nodes - if a decoy doesn't transmit any then it would be a suspicious, and if it does, then its hard work for a decoy to separate the real traffic from a potential attack.