I agree, especially for relating in general.
To me a demand in itself is not negotiable, as opposed to a proposal. And like you say, a proposal would have given you a better chance to get the pancakes.
In a previous business an employee made a demand for pay rise and said it was “not negotiable”. So I sacked him!
It was an intuitive decision and helped me to realise how important it is to keep negotiations open in business and personal relationships so that the outcome is committed to by both people rather than one person compromising themselves to please the other.