Product management glues a team together by facilitating a shared understanding of the market and what the product should do. Yet in some organizations product management is detached from testers. Just as product managers shouldn't write MRDs and throw them over the wall to product developers, they shouldn't throw them over the wall to product testers.
Product testers can play an important role in helping to formulate the requirements for a product. While testers may not have a lot of contact with customers, they have keen grasp of whether a requirement is testable, both in principle and in practice. Furthermore, testers are an audience for requirements documentation, as they develop system and acceptance tests from them. A product manager can use testers to help formulate the requirements in a clear and meaningful manner.