They are right. The root cause for polarization is wealth inequality which is caused by government fiat money printing; of which Facebook happens to be a major beneficiary. Facebook is therefore only a beneficiary of the problem and not the root cause.
Wealth inequality leads to inequality of opportunities which causes inconsistent experiences of the same economic system and causes polarization. One side's experience is characterized by constant struggle with repeated and almost inescapable failure (obvious glass ceilings everywhere)... The other side's experience is characterized by repeated success with little effort required and so they think that people on the other side must be extremely lazy or stupid.
Wealth inequality leads to inequality of opportunities which causes inconsistent experiences of the same economic system and causes polarization. One side's experience is characterized by constant struggle with repeated and almost inescapable failure (obvious glass ceilings everywhere)... The other side's experience is characterized by repeated success with little effort required and so they think that people on the other side must be extremely lazy or stupid.