The Big Three were objective sources. CNN in the 80s was an objective news source. This crapola we have now is of recent vintage. When people say "It's always been like this," they are rationalizing.
Up here, you had the Milwaukee Journal and the Milwaukee Sentinel. The former was the "liberal" paper and the latter was the "conservative" paper. If you took out the op-eds, they would read almost exactly the same in their reporting. What has changed is the insertion of political bias into the news copy of newspapers and in TV news coverage. It was not always like that.
And I have yet to have anyone come remotely close to explaining how you get objective news by consulting two biased sources on either side.