The difficult thing about talking about project management is that it is so inconsistent at different organizations that makes it impossible to talk about it without having a lot of context.

I worked at companies where project managers had very strong technical background and experience, but I also worked at a company where project managers were only a little technical, but had very strong project management skills. Then there is the other end of the spectrum, where project managers are simply incompetence. They got promoted to become a project manager with almost no knowledge about it and also no willingness to learn it properly and become good at it.

The latter (incompetence PM) is awful for any type of engineering work. And some companies make it even worse by making engineers report directly to those project managers.

The first type (technical project manager) is obviously harder to build, because not many engineers want to become project managers, and not many engineering teams are able to navigate without a good product team in organizations that don't have a solid engineering culture (e.g. traditional companies). So you often find companies with the second type. And even then I think it’s best if there is a clear separation of concerns between product and development teams. A product manager/team that takes care of product concerns but not engineers themselves. While they work with each other, engineers should report directly to a technical lead that understands their efforts and needs.