Although there is an article provided as evidence for this claim, after reading it, I don't fully believe that it fully supports their claim. Although yes, it's true that white meat is lower in fat and calories, dark meat is still not bad for you. When looking at the article eating well, they state that both of these meats provide good, healthy, and important nutrients. White meat has its own benefits for individuals like being higher in protein and lower in fat, but dark meat does as well. Dark meat has more amounts of iron, zinc, and some B vitamins which could be better for certain individuals.
https://www.eatingwell.com/white-meat-vs-dark-meat-which-is-healthier-8416235