They could potentially have this... if they didn't filter or limit content at all (Safe Harbor) but Facebook (and Twitter) have explicitly chosen to do otherwis

They could potentially have this... if they didn't filter or limit content at all (Safe Harbor) but Facebook (and Twitter) have explicitly chosen to do otherwise. They want to control what content is posted to them, very much so. Facebook (and Twitter) want to have a particular narrative, and one that's ultimately to make their advertisers happier. If you don't agree with that (and, imho, you should take issue with that) then choose an actually free platform. One controlled by an American for-profit company will never be a truly free platform.