It's solidarity with a potentially wrongfully terminated employee that was critical to the site itself. She was loved by community, critical to the function of the site and fired without cause + without a backup plan to replace her. 75% of the site is down and more of the subreddits are planning to go dark still. /r/sports is considering joining as are mods for others.
Explanation from a moderator for why they have gone dark
https://np.reddit.com/r/OutOfTheLoop...rivate/csq204d