Since the other thread was closed before I could reply, and it’s at least somewhat on topic here, I want to reply to your question:
A single-player game exists for the players. A multi-player game doesn’t exist for the players, but neither do players exist for a multi-player game. In a multi-player game, players exist for each other. Because everyone is connected to each other in some way or another in a game like EVE, players have obligations that go beyond seeking out their own pleasure and nothing else. Of course they can only seek out their own pleasure if they want to, but that leads to the problem of the commons as I mentioned before.
In the case of mining as per this thread, for example, if all miners only focus on mining as much as possible, then this attitude will lead to a situation in which none of them are able to get meaningful compensation for their work.