If every sprint fails but the product is stellar, was scrum working or failing? I'd argue working.
My initial conclusion: success. If a process is a series of steps taken to achieve an end, a stelar product is fulfilling the goal.
I think the underlying idea of you statement goes in the direction of: People and relationships over tools and process. In that matter, I agree wholehartly.
But just for the sake of debate, I'll take a healthy second guess:
A stelar product validates itself, not the process.
If process should encompass progress in time, then let's add complexity: time and friction. As a developer, failing sprints means lower self steem, higher pressure. If I was given a task to be done in a period of time, not delivering means im failing. Since I am a team member, I value the jugment of the assigment as correct. Someone stimated that had to be done. Someone trusted me. If I dont make it, im failing that trust. I work longer hours, get start my day tired. Its harder to deal with me.
As a project manager, now i have to deal with stressed out developers. I have less laverage, more preasure. Its harder to tranlste client needs to the team.
As an accoutn manager, i see the development of the project as problematic, i foresee failure, so I feel in debt with the client, then Im more linient to agree with anything.
As a partner, since i have to mantain a relationship with the client, i might be more willing to understimate this project in onerder to maintain that relationship and keep the next one.
You get the picture...
Metrics, how you meassure success. Its hard to go methaphysical and dont get into epistemology or ontology...who we are, what we do, and how we do it? If we are HUGE, you expect a high turnover rate, then you can bear a process that taxes individuals.
Added value of process.