I'd say that the Jake Tappers of the world were just very uncurious. I wouldn't call it a "coverup" -- more of a "look-away."
Former NYT editor Jill Abramson summed it up pretty well:
But I do think if enough reporters had pushed, the story was reportable. I worry that too many journalists didn’t try to get the story because they did not want to be accused of helping elect Donald Trump. I get that.
But this is no excuse for abandoning our first duty, which is to report the truth and hold power accountable.
I do not think this had any bearing on the outcome of the election. But Abramson is essentially conceding what many of us have said for a long time: that most of mainstream media is effectively a mouthpiece for Democrats. Of course they were afraid -- not just of potentially hurting Biden, but of "being accused of helping Trump."
Accused by whom? Well, their colleagues and peers, of course.