Managers are responsible for careers: hiring, development, satisfaction, promotion, visibility, and so on. Senior ICs (L5+) are responsible for the work. They own their products and domains, including architecture and long-term roadmaps, and are ultimately accountable for its impact. I did get myself that promotion... it was called Senior Engineer.
We have people who do JIRA tickets specified and prioritized for them ahead of time by others. They are called Engineer I and Engineer II. They don't get paid nearly as much or have the autonomy and recognition that senior engineers do. Most of them are biding their time waiting for managers to finally find projects they can drive instead of help with, so that they can finally demonstrate senior competencies and get the title themselves.
I guess it's just a difference of nomenclature theb. FAANG (especially Amazon and Microsoft) are just so big that the stratification creates a lot of roles to facilitate the org. Even at my old company (~5500 staff), our managers only owned one product but I guess your RM would have an entire portfolio.
We have people who do JIRA tickets specified and prioritized for them ahead of time by others. They are called Engineer I and Engineer II. They don't get paid nearly as much or have the autonomy and recognition that senior engineers do. Most of them are biding their time waiting for managers to finally find projects they can drive instead of help with, so that they can finally demonstrate senior competencies and get the title themselves.