Why does direct production limit the quality of life?
Direct production is the system in which people make the things that they need instead of buying them from other people. This limits quality of life because it forces people to do all the work themselves instead of benefitting from the talents of others.
Let us say that I am a good tailor. I can make nice clothes quickly and efficiently. In a system of direct production, I would also have to grow my own food and make my own tools. Let us say I am not so good at that. It would be better to have a division of labor where I make clothes, someone else makes tools, and a third grows food. We could all do what we are good at instead of wasting our time making substandard products.
Direct production limits quality of life because it forces us to do everything ourselves even when we are inefficient and unskilled at some tasks.