If you want to sell newspapers in a big city like LA or NYC, the majority of your customers are liberals. So, you pander to them by endorsing the Demagogue. If you endorsed the Republican, you would lose subscribers. The people reading the NY Times, LA Times, Boston Globe, etc., are going to vote for the Demo anyway, so the endorsement hardly matters. Also, normal people around the country never look at those commie rags, anymore than they read Pravda.
I think it makes the most business sense to have a moderate editorial stance and objective news coverage.
A lot more people would read and advertise in the newspaper under those circumstances.