I'm thinking of specific people on my server (which I'm sure we all can). The type that seem to only play the game to antagonize others in public channels. I could see a silence penalty being worse than a ban.
Bans usually have them return irate about how they were wronged and with renewed vitriol. The silence could feel like a slow, agonizing process. Having the ability to still log-in, I highly doubt they have the self-control not to.