OP said “product manager” which is also wrong. Funny how these three very different roles constantly get mixed up by smart engineers.

Maybe because from the POV of engineers, they all look kind of the same and half of it doesn't make sense.

The bad version of all three look exactly the same. And the bad version of all three are actually worse than nobody at all. Yet, high management is completely convinced those people are essential so they'd rather keep a bad professional there than get rid of them.

Anyway, the good version of those three are completely different, and add a ton of value on very different places. I think they are rare enough that many people don't ever meet one of them.

It would make things a lot easier if it was all one big AI. Lets refer to it as The company.

Titles--bloody titles! The AI doesn't care what its title is.