Promise the moon and deliver essentially nothing.

promise the moon, 这个短语的含义不是指“对着月亮发誓”，其正确的含义是：

promise the moon (to someone) 向（某人）作无法兑现的承诺； 作出过度承诺

Like most governments in their first term of office, they promised the moon.
像大多数处于第一个任期内的政府一样，他们也作了无法兑现的承诺。

Bill will promise you the moon, but he won’t live up to his promises.
比尔向你作出过度承诺，但是他不能践行他的承诺。