Project Management is a VERB. Project Managers "manage" projects. No matter what anyone tries to tell us, projects don't manage themselves. There are many styles of project management. Even some where the role of the project manager is distributed - self directed teams for example. But in the end projects are human activities that require some form of bounded guidance.
Along the way there are many questions that needed to be answered. Here a short list.
Each answer can be a document (and is a document on any non-trivial project). The contents of the answer can vary depending on the complexity of the project. From some notes on the White Board to 100's of pages of detailed narrative and diagrams, to a multi-million dollar ERP system containing the data for the program.
But in the end if you don't have some grip on the answer - in a way that can be produced when someone asks the question in the right column with some artifact in the left column, you're headed for the ditch and may not even know it.
So when we hear about all the failures of projects, especially in IT, let's ask of those failed projects had answers to these questions before concluding that the project management approach was flawed and needs to be replaced with an even more flawed project management approach.