I believe this is one of those cases where the person in question would actually not mind what you buy them because they care more about that you bought something for them than what the actual present is.
Maybe I'm just seeing it that way cause I do the same.
This year for my birthday my sister was asking questions about the cake because she wanted to make it. I legit didn't care about the details cause having someone take the time out of their day to make you a cake is more important than "Yeah, it has to be this flavor and it had to be this color and", or at least to me it is.
I can totally see how it's an unhelpful answer, and I'd probably curse someone if I were on the receiving end of that kinda answer, though.