"Journalistic objectivity" has more to do with professionalism, accuracy, and standards of evidence than with the absence of a personal perspective on the news.
What I also notice is that Americas in the early 20th century weren't very ideologically divided, though Lippmann and others may have tried to make journalism more ideological.
Reporters started out on sports or crime and worked their way up to covering politics, foreign affairs, and the arts. A nose for news was more important than a political ideology or animus.
They probably disliked the rich, but they didn't have the politicized worldviews that today's journalists have, so something like even-handedness or factuality or disinterestedness wasn't considered a wildly impossible ideal.
The fundamental thing which unites journalists, IMHO, is a desire for influence. This motivates journalists to despise “The man who is actually in the arena” and to promote the conceit that, pace Theodore Roosevelt, it is the critic who counts. This leads directly to the cynical idea that “if you’ve got a business, you didn’t build that - somebody else made that happen.” That is the obvious nexus between the interest of journalism and the interest of socialist politicians.