What is wrong with allegorizing, spiritualizing, or moralizing the stories in Scripture — like the David and Goliath story?

it created unrealistic expectation that clouded people's logical reason.

Explanation:

The story of David and Goliath Tell an unlikely victory where a smaller soldier beat a much larger soldier in a battle. The scripture mentioned that Goliath was around 9 Feet 9 inches while David was around 6 feet tall.

Spiritualizing or moralizing such story often give a perception that people has the ability to always come up on top regardless of having big disadvantages.

But in reality, cases such as David vs Goliath will ended up with Goliath crushing David the Vast majority of the time. People need to realize that moral and spiritual value from stories like this often times wouldn't be something that you can follow in real life situations.

If people face big advantages in a conflict, most of the time disengaging will be the best course of actions.