As you mentioned, it's quite new. I haven't actually seen the document yet. I know that social media platforms have always fallen under safe harbour provisions that do protect them from the content that people post on their platforms. Back in the day, we considered it a positive thing because we didn't want to hold Google responsible for someone else uploading content. Google Search would not function, or we wouldn't have it today, if Google was going to be responsible for organizing certain kinds of illegal information.
When it comes to actually holding Facebook accountable with regard to Cambridge Analytica, I'm also not quite sure what the implications of this new agreement would be, but I do think it's a really important question. I'm sorry that I don't have more insight.