This may be something that helps some people. There has been a vitamin D promotional to health care providers for a number of years for various problems. It's been given to the elderly supposedly to 'prevent falls' although research fails to find any evidence that it does, also recommended with Calcium for (absorption/I forget---the nurse is getting old) and taking Calcium/D again is not supported by the evidence over time and studies. In my career I noticed a number of supplements and medications that were touted for a specific purpose and, when it became clear it didn't work, another "purpose" was tried.
I wonder if enough depends on genomics that there are benefits for some, not others.
Or, it is just marketing. (genomics: eg-you can be tested to see if you will benefit from certain treatment for Hepatitis C...)