That was what civilization was founded on. Capitalism came many iterative ticks later. It's actually way less exploitative than the regime it replaced, feudalism.
"Farm this land, and make as much as you can, and give us the surplus, or we'll kill you and find someone who will."
"You mean I don't have to wander around the land responding to threats, you'll do that for me? If someone else comes around and threatens me, I can just point them to you? I can sit here and just figure out how to increase my YoY crop? Buddy, you don't have to coerce me, just swing by every month and we'll wine and dine the fuck out of you! I sure hope you brought all your horses because you're gonna need em!"
Warlords were like helicopter bosses. Annoying, but they don't stick around long enough to really mess with anything. It's those with misplaced senses of justice that really got a bee under their bonnet over it. Same as today.