First the Bad.
On the extreme end of purely adversarial games, is a mechanic that many people dread. Player elimination. Losing is one thing. But being eliminated?! And then everyone just plays on without you! About the most pure example of a mechanic which is fun so long as it never happens to you. And especially not if you are first. Of all the stories of rage quitting that I've heard, an early player elimination is the most common theme. Especially when the average length of the game in question is basically an entire day. Nobody wants to be kicked out of the game, with the prospect of having to wait hours, all alone, for a chance to play with people again.
Some games are awful because they were designed around player elimination concepts, but don't have player elimination. Instead of players being eliminated and the game ending, players are forced to continue on, in some sort of zombie state, until the end of the game. They get to do a single default action, over and over, every turn. Like taking 2 resources. Or placing a single combat unit in a single area of the map.