Is Steinbeck a "neutral" observer/chronicler of the human condition? What examples from The Grapes of Wrath could support this?

Steinbeck, in The Grapes of Wrath, is
not in any way a neutral observer.  Or, at least, his narrator is not a neutral
observer.

The novel presents what it presents from only one
side.  It is not a fair representation of both sides of the story.  The work spends no
time presenting the point of view of the owners of the lands, etc., featured in the
book.  Everything is from the Joads' point of view.  The Joads are the heroes and the
owners are the villains. 

Some writers and scholars believe
that the one thing a novel can do that no other art form can do is present a fair and
thorough presentation of all sides in a conflict.  This kind of novel most fully reveals
the human condition, or human existence.  Whether you agree with that or not, it is
certain that Steinbeck's novel is not that kind. 

His novel
is designed to present the plight of the victims of the dust bowl, the depression, etc. 
It is not at all written to reveal anything from the point of view of the landowners and
business owners.