By partnering, the Business and IT become one. The business and the customer are continually involved in the lifecycle of the service rather than just the front end. In the past it used to be the case but by using ITIL we open ourselves up more to the customer.
Partnerships bring about great advantages such as knowledge sharing, better communication and experience. By partnering, the business and IT are aligned to focus on the goals of delivering the service. Using synergy, different entities cooperate advantageously for a single outcome, we can produce an overall better result than if each group were working toward the same goal separately. "The whole is great than the sum of the individual parts".
A great example of how emergence can be beneficial comes from nature itself. Individual atoms can be combined to form molecules such as polypeptide chains, which in turn fold and refold to form proteins, which in turn create even more complex structures. These proteins, assuming their functional status from their spatial conformation, interact together and with other molecules to achieve higher biological functions and eventually create an organism. This 'lego' type building of individual items to form larger more functional units is the basis for ITIL partnership. If teams, departments and the business emerge, then the overall business engine functions at a much higher level.