If someone on Facebook says something blatantly slanderous / libelous, you can't sue anybody. Ditto with Youtube, etc. etc. So if you're going to say disinformation, its best to do it on Facebook.
EDIT: Downvotes? I'm sure everyone has heard the story of "Liars on Facebook / Amazon reviews / Yelp are killing my business". You literally can't win vs the liars on these platforms. FoxNews / CNN are legally not allowed to make libelous / slanderous claims. But go to Facebook / Amazon Reviews / Yelp (etc. etc.), and suddenly you see slander / libel / lies all over the place.
Because our laws are ineffective at policing that behavior on the internet.