This is so much meat and dairy industry propaganda it's comical. But people believe it because it is easy and they want to.
Oh, really? My great-grandma was dead-on with regard to smart eating. She lived it, she quietly preached it, and has several generations of offspring who ate likewise and where ZERO obesity or weight problems occurred. I just came back from a family reunion, and it was remarkable, but not, if you knew the fundamental nutrition theory of the folks there, which is pretty much that "industry propaganda" you suspect.
Some of us are genetically better suited for dairy, others are genetically predisposed to lactose intolerance. Regardless, eating food the way God put it in front of us is the best way to go.
One of the fads that will go by the wayside one of these days, is the all egg white kick. You need the yolks, and "science" will discover it sooner or later. When you only eat the whites, you're getting an incomplete package. Yolks are also one of the rare dietary sources of vitamin D.
I guess you didn’t see the recent news about saturated fat.