I think that we can agree that if you want to become a generalist programmer, able to hop from random web startup to random web startup, then a PhD is probably

I think that we can agree that if you want to become a generalist programmer, able to hop from random web startup to random web startup, then a PhD is probably not that useful. If however you want to become more of specialist, say being able to develop novel solutions to complex fluid dynamics problems then a PhD is very useful place to start.