> Here is the thing: The purpose of a PhD is to demonstrate the ability to conduct scientific research independently. This is field-dependent. In some fields,

> Here is the thing: The purpose of a PhD is to demonstrate the ability to conduct scientific research independently. This is field-dependent. In some fields, undergrads can already be independent researchers. In other fields, even postdocs are not independent, as doing research requires funding, materials, and labor. The latter is the real problem, as professors in those fields need a steady supply of PhD candidates to do their research.