Given the low lifespan of angels on the battlefield, the short operating time of most puppets seems like it wouldn't be a disadvantage. I've said this before, but I'll say this again: the only reason war isn't totally automated and fought by expendable puppets is probably due to economics and greed, along with probably at least a bit of laziness. Given the science and technology available to the humans in this manhua, they could easily do away with the need for war and poverty. It's just rigged economics and greed that stops them from doing it. They have the knowledge, technology, and infrastructure.
Which is eerily similar to the situation we have today. We have the technology and science to eliminate all poverty and hunger, and many forms of disease. The only reason why we haven't is greed, and the lack of desire of the people who hold most of the wealth and resources to want to share them. Same reason the planet's being polluted to death. Not because we can't use green manufacturing and technology, but because the elites have determined that it's not "profitable".