Why are Schedule and Cost Management Plans not outputs of any Process?

Harwinder

Why are Schedule Management Plan and Cost Management Plan not explicitly listed as outputs of any process, but are listed as explicit inputs to various processes (such as Plan Risk Management)?

Ref: PMBOK Guide, 4th Edition, Figure 11.2, Page 277

Similarly, why are Knowledge Areas (instead of Processes) shown as input sources in some Data Flow Diagrams? This is related to the previous point. For example, Figure 11.3 Plan Risk Management Data Flow diagram shows Project Time Management and Project Cost Management as inputs to Plan Risk Management, with Scope Management Plan and Schedule Management Plan respectively as specific inputs.