I'm not saying engineers can't do the job; many engineers certainly are capable of working as product owners, and in most cases startup founders are their own p

I'm not saying engineers can't do the job; many engineers certainly are capable of working as product owners, and in most cases startup founders are their own product owners, regardless of ability (for better/worse, but usually for better if they're succeeding). Rather, the point is that it's an extraordinarily critical function and not something to assume everyone is just good at because they say so or because they're "smart" in some sense.