I don’t know why misophonia isn’t more well-known except that according to Wikipedia, “As of 2019 there were no evidence-based methods to manage the condition.” I guess not enough research has been done on misophonia, and not enough experiments and surveys have been taken from people who present symptoms. I found this article helpful in shedding light on the subject:
https://www.livescience.com/65669-what-is-misophonia.html