I think the big media companies probably knew this too but needed to create a false horse race for ratings and clicks
I mean, either every single pollster in every major news organization was just terribly off on their prediction or there was a push from the ownership to make this election 'more interesting'. (This is my own conspiracy theory and I have no sources to back this bullshit up with)
you're right. I have to admit after the election I shut out lots of political media and really missed that it was closer than I thought.