Let me start by quoting Harvey Levine. “Where Six Sigma propelled us closer to zero defects.  The PPM process will move us closer to zero project failure.”
 
There is a very powerful counter argument against R. David Hofferberth Project-Centric Approach - click here to read his article. 

This argument is the case for Project Portfolio Management. 

The project centric approach has been around since the dawn on project management and is inherently flawed.  Why?  Typically in project centric environments, organisation tend to focus on individual project choices, made one at a time with little regard for the impact that one project has on the next. Moreover, project-centric tools and processes typically have the reputation of being in the domain of the project manager, not that of the business, divorced from the executive decision making stream.
 
The result is poor quality project information and an imbalanced portfolio which leads to project-by-project decision making. In other words, the business suffers from too many projects that have a bias toward the short term, which are relatively low in value and carry minimal risk. When riskier projects are put onto the agenda, management does not have the necessary visibility of the business’s capability and is not prepared to initiate the project. Most importantly, a project-centric approach is unable to roll milestones up and down the organisation in order to give a business view of what is
and what is not being delivered.

I  argue in my new book Project Portfolio Management: Leading the Coprorate Vision the following. “PPM challenges the narrow ‘pure play, project-by-project orientated focus to planning’ and draws attention to the broader, more integrated approach, which subjects projects to wider organisational considerations and executive responsibility.
 

Simply put, PPM looks to empower the business, not just the project process. It helps the business establish a clear line of sight from the top-level pan-initiative view right down to the individual project layer. From the strategic viewpoint, it allows stakeholders, business leaders and executives to see clearly and understand how effective their strategies are and if necessary which programmes and projects to review. From the operational viewpoint, PPM empowers programme, resource and project managers with tools, support and necessary corporate accountability to execute project delivery.
 
The management of the project portfolio so as to maximise the contribution of projects to the overall welfare and success of the enterprise. Project Portfolio Management (PPM) is the management of that collection of projects and programmes in which a company invests to implement its strategy, for example asset programmes, improvement initiatives and strategic change work streams among others. A PPM process can utilise various techniques to provide tangible results for your business, ensuring that project investments contribute directly to realising your corporate goals.”
Let me finish where I started by quoting Harvey Levine.  He states that” The emergence of PPM as a recognized set of practices may be considered the biggest leap in project management technology since the development of Program Evaluation and Review Technique and Critical Path Method in the late 50s”