Budgeting, analysis of any sort of proposal, and anything that has to do with funding is the responsibility of the purchasing function of the typical business model.
The purchasing department is the main provider of the business. It accounts for everything, from the amount of money spent on utilities all the way to how much coffee costs when provided in meetings. This department makes all the decisions concerning anything that will be approved: the business model states that all the revenue is to sustain and better the mission and vision of the organization, not to benefit people or persons in particular.
Therefore, budgeting ensures that everything used from the profits of the business is put back for the benefit of the business itself and those who sponsor it, as a result.