People doing a PhD immediately after their bachelors or masters are used as cheap workers by the PIs to do some subset of their main research, to write papers and TA.

I went back to do my PhD after more than 20 years in industry. Being an independent researcher gave me the freedom to pursue a topic that I saw a need for in industry. Of course, I'm biased by my experiences, but I do think we would make more practical contributions to industry if all PhD candidates had to gain industry experience before enrolling in their research program.