Answer:
In philosophy, idealism in the debate about perception refers to the theory where reality is ordered one's thoughts and plans. On the other side, Realism is connected to the fact that reality exists absolutely independent of ideas, thoughts, and even one’s consciousness.
So, the novelists and artists used realistic portraits of anonymous staff and celebrities as heroic symbols of strength in the face of adversity. They tried to share their art with a broader audience in early 20's.
Their goal was political because they liked to reveal the deteriorating conditions of the poor and the working class. And, they took responsibility for existing governmental and social systems.