That sort of rank partisanship can barely be hidden. It's discrediting. FB is clearly in the worse here, even if they were entirely within their rights while Cambridge Analytica was entirely not. What's legal is not always what's right.
It's becoming clear exactly what the cost of social surveillance is in our lives. This is just one of many significant problems with it.
There have always been jackasses willing to sacrifice morals (or rightness) in favor of power. Social networks just make it easier to ignore signals that should humanize power.