Section 230 allows anyone to be a journalist without facing consequences for false or incorrect information. This means a post on Facebook or YouTube or their own website has equal weight as a traditional news report that relies on higher standards, like verification through multiple sources.

So a company like Facebook can host any false or unverified article posted by some random weirdo, since Facebook can't be sued for hosting that info, and the controversy draws eyeballs and draws attention away from more traditional news content. So now the attention shifts to low-quality social media and away from traditional media.

Note that traditional media still had their own problems propagated through their ownership. We never really had high-quality independent media in the US, although the current indie-media landscape might have opportunities for growth the way they wouldn't have if traditional media still existed.