The JW Org wants us to be almost perfect. The slightest fault that we do, we are treated as if we are entirely bad, then we get DF'd.
It's an "ALL or NOTHING" way of thinking that can be spiritually dangerous.
Example: If a JW is caught smoking, and becomes DF'd because of this, that person may feel free to do even worse sins, because they can't be more DF'd than they are right now. So disfellowshipping a person for something as small as smoking or playing lotto, can be counter productive for the sinner.
It's like puting a person in jail for a petty crime. Then in jail, he gets to know real criminals, and comes out of jail worse than when he entered.