Big social media thrives on anger. It thrives on shock and antagonism. Showing you posts that will make you upset means you will boost the site's advertising revenue, and making posts that upset you mean instigators of the culture war can build their audience and reach.
Until they figure out how to make money some other way )perhaps through subscriptions), big social media will always play both sides in the culture war it helped to create, and it will continue to sell your peace and mental health to enrich themselves.