A common question is whether it is acceptable to combine the role of product owner and scrum master and give both sets of responsibilities to a single person. There is some overlap in the skills and personality traits that make good product owners and scrum masters. However, the roles are different, and it is unlikely that someone will be able to excel at both, especially at the same time.
Mike Cohn, founder of Mountain Goat Software mentioned in his recent blog that scrum masters should not also be product owners. He said that product owner and scrum master are focused on different aspects of a scrum project. The product owner spends his or her time thinking about what to build regardless of the capabilities of the team and scrum master concerns on team capability and capacity, therefore sometime needs to push back product owner.
While a product owner is determining what to build, the ScrumMaster is helping the team work together so they can.
Mike said that it is quite likely that being either scrum master or product owner requires full- or near full-time attention. Putting one person in both roles at the same time will almost certainly short-change one of the two.
Roman Pichler, product management expert and owner of Pichler Consulting, mentioned in his blog about the differentiation of the roles of scrum master and product owner.
The product owner and scrum master are two different roles that complement each other. If one is not played properly, the other suffers. As the product owner, you are responsible for the product success — for creating a product that does a great job for the users and customers and that meets its business goals. The scrum master is responsible for the process success — for helping the product owner and the team use the right process to create a successful product, and for facilitating organizational change and establishing an agile way of working.
Roman explained that scrum master should expect vision and strategy, product details and collaboration with the team, from the product owner. Similar to that product owner should expect team coaching, organizational change and product owner’s coaching, from the scrum master. Therefore there is a conflict of interest and focus areas in both the roles.
Mike said that though both the roles should not be combined with others, still there are some exceptions exist in organizations.
Certainly, I’ve encountered many situations in which the scrum master and product owner were the same person, and where I felt that was appropriate. Some of these have included small organizations that could not afford the luxury of dedicated or separate individuals.
Mike mentioned some other situations like in small teams one person plays both the roles of scrum master as well as of product owner or role of scrum master combined with developement.
So, sure there are exceptions—just like there are to any rule. However, none of those exceptions should exist for the long term. And anyone in both rules simultaneously should be aware of the challenges the dual role presents.