They did stop the counts in the middle of the night in 2016. My take is that they didn't have the physical ballots to dump into the scanners like they did in 2020. And they didn't have covid as cover to keep counting for two weeks to get the numbers where the wanted to be. In every presidential election since FDR, they morning papers printed who won. Which is why that pic of Truman holding up the paper that ran the story early about Dewey beating him is so famous.

Dems believed their own polls, and thought Trump was unpopular. They had, after all, with all the free media they gave Trump, effectively rigged the primary in 2016 to him, thinking he was toxic.