[overgard]

So: I don't really know, but I have a theory.

Good product managers are really really hard to find. I've had the pleasure of working with a few, but I would say about 90% of them are worthless. The gems are definitely worth having around though.

The problem is, since finding good product managers seems so incredibly hard, I think instead of hiring for it and making it an official title, most organizations just evolve someone into the role. The problem is, being able to be a good manager requires a lot more domain knowledge than a lot of people realize, IMO, and so it ends up that often times the best product managers are people that either evolved into it from a design or development standpoint, or a person that had a lot of good domain knowledge in the subject matter that could step in. The commonality of all the product managers I've know that weren't good was that they really lacked domain knowledge, to the point where they were basically trying to tell people what to do even though they were clearly the least informed person in the room.

[crimsonalucard]

I agree. Essentially, good product managers should have all the skills necessary to be a designer or developer as well.