For any organization, various functional plans-marketing, financial, human resources, production-have to be laid down, even though all the functional plans serve different purposes and all theses plans provide guidance and structure to the successful running of the business.
A valuable source of information about your business that may be required by third parties ; Improved use of your company personal resulting from participation in the business planning process ; Increased employee motivation ; Increased profits and sustained growth.
A business that makes sense and is going to be sustainable in the future is one that has that clear vision within which all the smaller parts contribute to make it successful.
It seems to have been put there to fill the need to attribute a certain sum to marketing. Make sure you are researching each point of your budget, make sure that you are giving it context and it makes proper sense within your overall plan.