Comment by TheOtherHobbes

Most PhDs don't move the needle because the point of a PhD is to learn how to do research, not to produce ground-breakingly original work that reinvents the entire scientific order.

That's orthogonal to domain expertise and general ability.

If you can survive a PhD there's an adequate chance you know more about your subject than an undergrad and are more capable of focused independent work.

That's what employers are buying. Which is why STEM PhDs still get more attention from the private sector than generic mass-produced undergrads.