Is the PMBOK helping PM career to progress toward executive levels?

First of all I want to say that this post is not against the PMBOK. I think that is the most complete guide in the world of project management. In this post I only try to explore some thoughts about PMBOK, regarding its business focus and the impact in our profession. In one of my posts, I was speaking about some barriers that PM profession faces in the path to executive levels. In this post, I will try to find what is the PMI point of view or it's possible interpretation in terms of a PM as an executive. There are many books about the value of Project Management, and most of them agree that is the most effective way for the organizations to deliver strategy and value. Practitioners also begun to speak about Organizational Project Management as a way to empower the project management by aligning all the organization with project practices. Besides, many books and articles are trying to shift the PM role to a more relevant and strategic position, because the PMs are the leaders that deliver the corporate strategy and business results. My question is: Is the PMBOK, giving the Project Managers a place or a role that is not so relevant (or with little importance) to the business, in some of its concepts? In the "Project Initiation Management" chapter, the PMBOK says: "Project are initiate by an entity external to the project such as a sponsor… The project initiator or sponsor should be at a level that is appropriate to procure funding and commit resources to the project". Isn't it a restriction to the project manager work scope? Why the sponsor cannot be at the project level? Isn't it like saying that project managers will never be involved in business definitions? Why Marketing departments, for example, don't work from the project perspective or with project management background? We know that the business case is an input to the Project Charter, but: shouldn't the project manager be involved and leading the business case development? Shouldn't the PMBOK include a guide to the project business case development, having the business need and the strategic plan as an input? After all, everything is a project! One of the Project Charter information is the Summary Budget along with the assignment of the project manager. Is a good think that the project manager gets involved with the budget that way? Shouldn’t the project manager be involved in the summary budget estimation? After all, this guy will be dealing with it for the rest of the project implementation. The same happens with the milestones. After all, who is the more experienced to estimate summary milestones and budget? Although the Chance Control Processes are managed by the Project Manager, and maybe the ultimate decision maker, there is no link between the changes and the business convenience or business driver for the changes. Why is so important the "on time and on budget" approach? This is a very restrictive approach because it limit the project manager responsibility to the project and not the product or the marketing of the product of the project. What if an increase in cost is allowed in order to deliver more features, needed because of changes in the market or competition? This change management approach is far away from the way businessman often think.