Every consular officer who does interviews hold this power.

Their words are literal laws backed by the fulll authority of the US, irrevocable and undeniable. Millions of people applying for a visa in the country they work in is subjected to their judgement without any recourse. There is no questioning their authority or their decisions even if everything they said is based on a passing whim. No, I am not exaggerating. Their whims is reason official enough to deny a person coming to the US and potentially changing their entire life forever.

Imagine that amount of power vested in what amount to a politician in training.