I partially disagree. The point of the PhD process is not to create knowledgeable, creative, courageous scientists. As you point out, they can (and do) come to

I partially disagree. The point of the PhD process is not to create knowledgeable, creative, courageous scientists. As you point out, they can (and do) come to be that type of person on their own. The value of the PhD is to teach the budding scientist the process that surrounds modern science. It's an opportunity to learn what the social structures in the field are (societies and conferences), to meet fellow scientists and form a network of people to draw on for ideas and criticism, and to learn the vagaries of funding and formally writing up research. Having a PhD says "I know how to do all these things... I know who the important people in my field are... I know which conferences are the most important... I know how to get funding". All of these things are important things to know if you want to do science professionally, because you need the connections and the funding to put food on the table. This isn't to say the PhD is some magical permission to do science. Lots of great science is done by amateurs, and more power to them. So scientists don't need a PhD to do science, but it is more than just a credential. It's a valuable training program on how to navigate all the social and bureaucratic things that surround the actual science.