You mean quotes like this one: "It is a nanite virus carrier. You drop those when you need to control a population, doesn't kill them, just makes them sick, like a flu."?
Call it naive science fiction that is utterly clueless about Complexity interactions and leave it at that. Nanites would have massive control problems. Interaction with the immune system would be a nightmare - and that's for the 'helpful'ones. The weaponized ones? Oh, they'll never get out of control, sure. Grey Goo is the perfect term for them, and delusion is the term for people who would unleash such a horror. We can't even stop the common cold. So hey, let's just start unleashing self-propelled, autonomous, molecular machines inside the human body and into the biosphere by the trillions. What could go wrong? LOL!
Well yeah, there's that.