I know this isn't the flavour of the thread, but his execution of his ideology would actually use up more resources. Thanos cutting the population in half means that he is cutting each race's knowledge in half. Any complex race would immediately not know how to do half the things it could do before, which means the majority of things it couldn't do before. Imagine a surgery where half the staff were gone. Yay! You have the heart surgeon, but you don't have the anesthetist! Patient dies!

? But there hardly any (none that I can think of really, but I'm sure someone will come up with something) professions that only 1 person performs that someone else couldn't figure out, and isn't documented somewhere.