Sounds like you've never worked with a good PM. A good PM knows the product and problem space extremely well, and guides the engineering team on what needs done. Yet at the same time sits back and lets the engineers devise the actual solution. They talk to all kinds of stakeholders, internally and externally, and build the roadmap. They know if an incoming bug is urgent enough to do right away, or how long it can wait. And they know which incoming feature requests should be done, which should be modified to fit a broader audience, and which are simply one-off bad ideas.

All that being said, there are engineering teams where the leads know all this and do all this. There are more engineering teams where the leads think they are good at this, but really just run all bugs and requests into the product in FIFO mode. The point is that somebody should be in this role of deciding what gets built through a deep understanding of the "why" of the product. A PM who does this job well brings a ton of value. A bad PM kills products and teams.

My advice is to care just as much about the quality of your PM as you do about your boss when making career decisions.