I would be very skeptical of such claims, especially from an article that notes that the 6' 10 1/2" man has things so much easier than his 6' 5" father.
Ive spent time in The Netherlands and certainly didnt encounter a large number of unusually tall people nor did the average height of men seem any taller, certainly not the women. I suppose all these giants might be hiding in rural areas somewhere but I know they arent in town. As far as short people, Ive never met a Japanese person as short as the Hmongs around here (and those all have access to the "taller" American diet).
Averages are regularly thrown into conversations where they have no place for the purpose of manipulating toward an intended outcome and really shouldnt be taken too seriously most of the time. I have no idea what that researchers angle might be. For example, the average human has one testicle, its all the rest of you with a different number that are the weirdos.
They actually determined that because of the Winter Famine of 1945, it lowered the average height of the Dutch after the war.