Product Owner and Scrum Master....why both are valued and necessary.

In my recent experiences, I'm asked about the role of the product owner and Scrum master....why are they separate. My first reaction is...what do you mean? They do distinctly different roles. But in  a place where resources are leaned out so much...are these two roles a luxury? I must admit...I've always valued these roles as a coach...As a mentored the team giving them the reasons why...it's so important to have these roles with such different focuses...I wondered..

In my explanation I use focus as the driver of the discussion...where is the focus placed?

• For the Scrum Master, the focus is inwards...on the team and the process.

• Is the sprint going well?

• Is the team happy?

• Are they learning what they desired to learn?

• Are they focused?

• Can they accomplish their goal? When they do, do they feel a sense of accomplishment?

• Are they empowered?

• Do they have autonomy to make their own decisions?

For the product owner, the focus shifts outward...toward the business and the stakeholders with the primary focus being around creating the stories for the team. 

• Their focus is on the customer and the folks using their products

• Getting feedback from the users

• Writing incremental user stories based on input from users and stakeholders

• Doing User research

• Preparing experiments

• Collaborating with the team during the sprint rituals.

There's so much value that both roles add to the mix of the team, the collaboration of the team and combination of skills. 

What are your thoughts?