This is the typical pop-sci cycle, and it happens over and over again. Someone neatly packages and oversimplifies a concept (power posing, the importance of sleep, even thinking fast & slow), which is swallowed whole and heralded as a wonderful insight by the general public, bringing the individual fame and fortune. The concept is then dismantled over time and found to be at best, 'difficult to replicate', and at worse, just made up.
The Piaget stages and psychoanalysis are a couple of examples that come to mind. Both were topics of the psychology textbooks belonging to my roommates.
I have asked experts in a variety of fields about how they cope with the replication crisis, and the typical response is: "Yes there is a lot of bunk being published, but we know good research from bad."
This has included people with advanced degrees in psychology, business administration, and medicine.
Reading this comment, it felt like you were describing the education system.
I'm waiting for someone to write a best-seller on the "Heat Theory of Education" [ Knowledge, in a given domain, flows from a knowledge-hot person to a knowledge-cool person, proportional to the differential, with some things between them acting as insulator or a conductor ]
It would be a nice bulwark against the pervasive meme that 'teaching is domain-less' aka "if you know how to teach you can teach anything"
I've been studying teaching a lot lately, and one of the things all of the books say is that mastery of the material is required but not sufficient to be a good teacher. The other skills, which basically come down to organization and emotional intelligence seem to be universal. In other words teaching as a skill is domainless but being a good teacher requires subject mastery.
Article mentions a longitudinal study of this theory but the study was criticised for selective data.
Article mentions that Ms Kubler-Ross started researching spirit media and the likes which would have contributed to her decline. Nowhere is it clear that the theory itself is flawed or "fallen".