I agree…the hardest part of Scrum is finding someone willing to sign up to be the Product Owner. In traditional waterfall driven projects, everyone gets to state “requirements” but the PM winds up owning the result — if they are good, and have an understanding of the business, they might be able to deliver a successful product. If not, the PM is at fault since he/she owned the delivery of this diverse set of requirements. The problem is, if the PM is brilliant at the business process, delivery and politics they have a chance to be successful; if not, lots of money and time are wasted.
Scrum move ownership from development teams (typically IS) to the business (Product Owners) in a very dramatic way that also moves perceived risk. Now, the business can be blamed for a failed project due to poor requirements and it falls on to the Product Owners to achieve some level of collaboration between groups, if not consensus. Unless senior (C-level) business executives buy into this, Scrum will fail on all but single departmental, small projects.
For more, please also see the thread “Problems with Agile Development”.