There are those who view everything in the light of politics. The point of art is to transcend politics, even when it's political, i.e. Richard III. But you'll never convince some people of this fact, either on the left or the right.
Richard III of course was blatantly political as was much of Shakespeare's output. RIII was a hatchet job and as historically dubious as anything Oliver Stone ever made. It's also his longest play and not quite good enough to justify the length.
"The point of art is to transcend politics, even when it's political, i.e. Richard III. But you'll never convince some people of this fact"
Art can have several points. One of those is to say something true about the human condition. Politics is a part of the human condition. Ergo, it is not necessary that art always and only exclude politics.
You brought up Steinbeck, and some of his works are blatantly political.