Wild stab from an idiot: it depends on what you're trying to do. Generally speaking, if you want to advance a field, or just do top-of-the-line work, you need to be an expert; but if you spot an ignored or underserved group of potential customers who could benefit greatly from a more basic implementation which the experts might find pedestrian and uninteresting, you might be on to something. In that case, your lack of expertise could even be a strength; you might understand you target group's difficulties better than the experts.