The main thing that a student should learn as the result of studying for a PhD is how to be an independent researcher, which means being able to formulate new research questions, generate hypotheses, design experiments to test hypotheses and analyze the results. Another important aspect of research is being familiar with the work of others in your field (which means reading lots of papers), both as a source of ideas, but also for proper evaluation of your work. Sure, you will also gain some new technical skills in the progress, but that is not the primary goal. To be a researcher you need to learn how to gain these technical skills without being taught them, because if you are near the state of the art, there is largely nobody there to teach you anymore (other than by reading their papers).
The important question is why are you studying for a PhD, what to you want to do as a career? If this is not research based, the need for a PhD is perhaps questionable.