Glad that you liked the definition, Nikolay. Later in the same article I explain a bit more about the roles and mentioned that:

"My preference is for not having this separation of roles and having only PMs. If there are BAs and / or POs in a certain organization, my recommendation is for treating those roles as intermediate career steps that will evolve to reach the PM level, with increased scope and responsibility. The rationale for my preference is that by leaving the roles separate, the PM may make little or no specification and / or prioritization, delegating those responsibilities to BAs and / or POs. By doing so, the PM will lose important input to developing the vision and strategy of her product."