Community members that only contribute negative comments should be kicked out.
Community members that don’t add anything to the conversation when they post, should be kicked out.
Community members that don’t increase the value of the community, should be kicked out.
Any member who don’t improve the community should be kicked out.
It’s not as harsh as it sounds. If your members don’t add value, they’re adding flab.
They’re cluttering your interface. They’re distracting your community from it’s goals. They’re taking up your time. They’re slowling down the meaningful stuff from happening.
You'll be doing your community a favour.