I think everyone that starts dealing with buddhism and start to walk the eightfold path has some ideas and a certain motivation. It may be to become enlightened, or to be afraid of a rebirth into worse conditions after death. Others maybe just want to gain certain skills with meditation or at least feel more relaxed.
I think its all fine. So any belief that make us keep going is good to hold up our motivation. But also there are points why it becomes in my opinion necessary to drop beliefs.
In one hand its good to live according to precepts. Sure, we avoid to harm others and also us, thats really good. But in the other hand, if we do it because we are afraid of some kind of punishment like be reborn in hell or as an animal, its some kind of wrong intention. We have to go from the surface, the belief to a deeper understanding what dukkha is, how it is caused and how we can be free of it or go beyond it. When we understand how unwholesome karma leads to suffer we naturally will avoid it. Theres no doctrine needed, no belief. Also, if we become more compassionate, we dont want to hurt others in any way, we wont make them suffer. Rather the contrary, we feel with those who suffer, we try to help them.
Also, when we expect anything out of the buddha way, like attaining enlightenment, we will be driven by greed and of course we will never reach anything. We have to understand the dharma and drop the belief at a certain point. Otherwise it becomes a hindrance on our way. We wont be open, but closed to a small focus on an idea.