As nowadays research becomes more and more multi-disciplinary and complex mixture of many things, one trend emerges - separation between idea proposing and execution. This is kind of obvious result from one fact - proposal of such idea require significant experience, knowledge, and expertise in a wide range of fields while such person typically lack of enough time to spend only on one research project. As a result of this mismatch in capacity in intellect and labor, it is nowadays common to find a PhD student to execute well established idea whose proposer doesn't have enough time.
Actually, this is kind of traditional picture for PI-PhD student relationship in academia. But, something weird is that this happens more and more frequently even beyond PI-PhD student relationship. Recently, I heard many PhD job talk-level seminars, but many of them were just "labor" not a "brain" in a sense that their main topic of PhD is not proposed by themselves. Can we call them as PhD? I would like to call them as empty PhD. It is very worrisome that academic culture kind of drives generation of myriad empty PhDs... Lamentable.