So the company should rebuke some of their clients, causing them to quit for good? Never!
For a good reason, there is no rule against quitting.
And don't forget: It's but a computer game. Quitting is no offence against high society etiquette but the mere expression of "I don't like it any more". Don't expect too much respect for anonymous avatars from a gamer.
Disclaimer: I'm a golfer, I only quit for serious and unexpected reasons.