I tend to agree with you, but I wouldn't say their moral system is based on compatabilism, but rather on libertarianism. Their moral system can be adapted to a compatibilist base, but as you say, this is a confusing and difficult process, which for a lot of people ends up in them throwing away parts of their moral system (thereby proving compatibilism, ironically).

>Turns out that convincing people that they don't have free will is bad.

Within our society/culture which desperately clings to the idea of free will. People grow up believing this and a lot of patterns, beliefs and thoughts are based on this assumption. You can't just tell people this assumption is wrong and expect them to magically adapt their whole way of thinking to that. It's no wonder accountability, morality, etc goes straight out the door if it was always based on the cultural myth of free will.