You are missing the point: What generates higher ROI: (1) dev + PM (separate people) or (2) highly skilled dev who can periodically act as PM? In my experience, it is always (2). Any time that I hear a senior manager complaining about "expensive devs", I always ask them: "How do you balance cost and quality?" Most of them are stunned by this question and give a bullshit answer. The truth: Almost all orgs are better to hire far fewer devs who are very high quality, versus many devs who are lower quality. I never worked for Amazon AWS but the "pizza-sized" team thing is real -- from experience.