I respectfully disagree with this review: the question asks whether something is possible, and the answer says "No". It is indeed an answer.
Either we forbid the "Yes/No" questions altogether, or we allow answers to such questions.
As the person that deleted it I would make the argument that an explanation should be given with any statement as to whether something is or isn't possible.
The problem with yes/no answers is they could age with time. For example it might not be possible at the current time to do something but that might change in the future. This is something that might not be immediately obvious unless a reason is given.