This does not address the problem of “Michelle Obama is a chimpanzee” or the “holocaust did not happen” going viral in one of those communities!
I guess the benefit would be the ability to get updates from your crazy family members while not having to see everything they post?
Whether or not this is a net positive for the world is a different question.
That's obviously not the case in most countries on this earth. Holocaust denial for example is illegal across the EU.
I will also note that in most cases, these laws don't prohibit such speech unless it is done in a manner likely to lead to harm. How widely or narrowly that is commonly understood is a different question.