Understand the advantage of whole team approach

Unlike traditional software development models where a project manager was supposed to oversee the project plan and risks and issues around it, a QA manager was responsible for testing only, Business Analyst for requirements and developers for design and development etc , Agile encourages an open interactive environment.
People in Agile environment work as a self organizing team where a Business Analyst can do testing , QA guys can do automation and Continuous Integration and deployment set up and developers can do requirements gathering with product owners directly.No roles are defined. Everyone in the team is called a developer and supposed to be cross functional.The delivery is done based on the tasks instead instead of the roles.