IDesigners can ensure a steady supply of something using it for something instead of trying to kill it off completely.

In the case of people I think this is similar, not killing them any more but the opposit keeping them alive (just about) to get a steady the supply of money and energy for those 'jobs' that 'need' doing for empires (even the diluted ones that seem harmless are still this kind of this container
I feel and mentality that it progresses more of the same)

I got this idea for a very clear and clever Cory Doctorow @pluralistic

https://mamot.fr/@pluralistic/107797822329953790

And for another example how to harvest people see this plant example of having a steady supply of eating things instead of killing them...

https://en.wikipedia.org/wiki/Invasive_species#Invasivorism