You should really read the article. Because a couple of words in the headline are playing into your confirmation bias and misleading you.
FTA: "I find myself truly worried about only one scenario: that Trump will win reelection and Democrats and others on the left will be unwilling, even unable, to accept the result."
Not really the same thing as "The Atlantic told Democrats not to concede".
> Clinton has told Biden to not concede, even if he loses
Citation needed. Did she say not to concede ever at all, or not to concede if on election night things look to not be going his way? With the number of mail-in ballots, the latter is entirely reasonable.