I haven't seen any support for the articles which actually shows the effects of the policy will be good, rather than arguments saying "it's meant to be good". Which is a fallacy that affects many politics which later end up having adverse effects.
But ultimately bureaucrats are happy whenever there is an excuse to increase bureaucratic power.
For the particular point you're putting out, to justify the EU policy you have to at least show that 1) those media outlets would receive all that traffic that those FB posts generated if the FB posts didn't exist in the first place, 2) that this outweighs costs from abusing that policy (claims over fair use, e.g. youtube copyright system) and content that simply will not get reshared, even if fair use and linking to the source material, out of fear of triggering the safeguards mechanism
I was just trying to put in perspective WHY the politicians feel the need to do this. It's mostly backlash against Facebook for years of content stealing.
Youtube and itś content ID system are actually what this law wants to introduce everywhere. While not perfect, it's still better than Facebook, which seems to be lawless on copyright.
In fact, it's all about the music industry wanting higher licensing payments from YouTube: At least as much per play as e.g. Apple Music pays. They call the fact that they're not getting that today the "value gap" – THAT'S the undisputed reason/justification for this law (just google the term).
(Facebook, by the way, also has a content filter: https://www.facebook.com/help/publisher/330407020882707)