No, its not a "waste of time" completely. But c'mon, what takes 5 years to do? Cities can be built in 5 years, so why would researching one narrow and specific area take as long? ie. parental support in early child development has a beneficial role in child education. c'mon. Research is vital, but I am just saying, not impressed with a PhD degree.
My older sis is an MD and also has a DO ( osteopath).She started as a med tech and got her masters, then taught at a small college before she went to med school. This made her a really well rounded Doc and she may soon get on staff at the Med School at Ohio State. I agree that the MD is the gold standard of advanced degrees, no question about it. It has the most status and is a rough admissions process as well.
However, some fields do have a great deal of rigor when granting advanced graduate degrees.
My masters in physics was a lot tougher to obtain than my doctorate in science ed for example.
I think being a doctor of medicine is one of the greatest things an individual can do for a career.
In my humble opinion, you might consider other fields as valid and worthwhile , as it looks quite pompous to look down on the rest of us poor slobs with "ordinary" adavanced degrees.