You imply #Facebook, #Google, etc are taking entire #articles from news sites and posting them on their own sites. If that were true, I would agree with you, and it would be a violation of copyright law anyway.
They don't do that.
They show a short extract - sometimes just the headline - of the article, with a #link back to the #original site's story.
This drives traffic to the original sites, and buys FB etc a few seconds of "#engagement". They get little from it.