ZD,
You will note I did not say the Quinoa is assur, I said that there are those who are makpid, and they do have a real basis to do so. Your quote from Wikipedia does not respond to their reasons.
Please try to provide a reputable halachic source for your comments about things that are not kitnios. Wikipedia is not a source, nor is Google. And accepted halacha seforim (I am not talking about contemporary seforim) contradict whatever you have been saying.
“There really isnt much differnece between Cake and Bread.”
Yes there is. Even the basic bracha is different.
“Potato Starch cake and cookies is very common”
Only by Pesach, as Kosher for Pesach. You want to consider something ossur as a chashash chometz because of something made specifically for pesach??