Should I sign up with a third party affiliate programme or use the casinos ?

Is there much difference in between promoting a casino’s own particular affiliate programme than signing up for a third party affiliate programme such as Casino Blasters?

I realise that promoting a well known casino, is probably going to mean more conversions as the customer is more likely to feel more comfortable with dealing with a recognised company. However, if that really is the case, why doesnt everyone just promote individual casinos and not sign up with the likes of Fortune Affiliates and Casino Blasters. There must be advantages of promoting these affiliate programmes instead of the casinos?