How many reasons must someone give?? Their focus seems to be placed on finding the "right" person who is hyper-passionate for the company...they can't seem to get past this element in their interviews and are likely overlooking great candidates.
How does one answer this question without any standard of measure? They offered no indication of what is already set-up, what technologies are implemented, what their vision and direction is etc and expect you to name three things you would have learned?? There is a better way to ask this question that will result in tangible behaviours an interviewer can measure.