You're right, determining what's newsworthy is a biased process in and of itself. But that doesn't mean throwing the baby out with the bathwater, neutrality is still something we should constantly aim for, even if it's a moving target.

For example, if a media outlet compare actual vs expected turnout for a Trump rally and report that turnout was "lower than expected", it would be plainly biased not to do the same comparison for Biden. The lines are obviously going to blur at some point (where 'balance' involves publishing something far less 'newsworthy'), but it's a lot like the definition of pornography - you know it when you see it.

Besides, most modern media outlets are blatantly pushing their own narratives anyway - I'd say it's far more important that we fix this before moving on to the smaller problem of selection bias.