I don't think that Product Manager is exclusively a trophy job, if at all. It takes quite some skill to manage a product properly, maintain healthy product boundaries, create a sensible roadmap, combat feature creep, etc. A product manager's skill set can make or break a product.
I think PMs get a bad rap mostly because it can be less obvious when someone is bad. If you're a bad programmer and produce nothing, it'll (usually) quickly be discovered (though not always) even if you're good at talking. It's also easy to spot check in the interview before you hire them. If you're a bad PM, but good at talking - it's easier to pass the interview and it can be harder to know they're bad and fire the…
If you're long enough in the tech industry you've seen such people and learned to identify them with good certainty after one or two meetings.