i agree-i read a book on yezidis once...quite obviously it exists in response to mainstream islam.
You are definitly not knowledgable about Kurds and their ancient religions, and sure not about the history of the region. If you have visited or lived in the region you would understand more.
Yezidis wear Arab clothes, while they are pure Kurdish. Only to escape perscustion by the Barbaric ISlamic neighbours. It's very known that the Ahl-e-haqq and Yezidis never reveal their true religion to avoid perscution. I know couple of rituals of Ahl-e-haqq or Yarsanis which defnitly has nothing with Islam. ISlam has destroyed the beautiful culture of the Kurds. And all what you read is Arab and Islamic propaganda.
Well, if Izady doesnt know the topic well, then nobody does. After all, Izady wrote his doctoral dissertation on this exact topic at Columbia University (1992). Have you read his dissertation? You might as well, because it leaves not a shred of doubt that the Cult (or Yazdanism as he calls it in there) is a system of beliefs that is attested to even by the Sumerian and Akkadian records.
If you look at the Kurdish languish and understand how old this languish are, you will understand, that it has been spoken before many other languish. Therfor many languish is built on kurdish.