That's kind of curious logic. If a student is so accomplished that it's plainly obvious to everybody that they deserve a PhD, then the degree itself is just a f

That's kind of curious logic. If a student is so accomplished that it's plainly obvious to everybody that they deserve a PhD, then the degree itself is just a formality. What's stopping that student from leaving, if they want to? I'm sure it makes sense in the context of European academia, which illuminates the contrast with the US.