[xanderlewis]

I can see why you might think that; in some cases I'd agree. But there are parts of science — indeed of human knowledge in general — that are very difficult to break into if you don't have the opportunity a PhD affords. These disciplines also require perseverance longer than the average human. Without this system, we're not going to make fundamental progress.

I'm pretty sure that without the research done by people with PhDs and people who don't give up at the first hurdle, we wouldn't be able to be sitting at our keyboards now having this conversation. Of course, it's not for everyone. Maybe it's not for most. But I don't think you should write all of it off as 'signalling'. Some research simply cannot be done without several years of focus, outside of industry or 'the real world'.