Imagine a rumor going around in Whatsapp.
Lets say it violates free speech laws and is liable to be sued and the one who sues is sure to win.
Lets say he sues and wins.
It still doesn't matter. Rumor about the lawsuit and the falsehood of the original content is already old news. And is not as quickly spreading as the original rumor.
The perpetrators of the original rumor win the war to influence, in-spite of free speech protections.
Free speech protections and laws mean nothing and are toothless in face of modern mass media tech.
Compare it to the old days, of the news being said on TV or Radio or in a Newspaper. They too can spread wild rumors but have definite and impactful backlash.
That negative feedback mechanism is lacking in platforms like FB and Whatsapp.