Facebook is going through a Looney-Ville-Magnet phase the same way Craigslist did about 10 years ago.
With Craigslist, people just had to become more watchful.
C/L was usually not held liable for any dangerous outcomes.
There may be something in the Terms of Service that exempts them from most liability. Some conditions the user has to agree to in order to start using the service.
Facebook is far more an expansive, and specialized type of web service. They too may be guarded by a team of lawyers.
Still, something should be done about the growing frequency of people committing serious crimes and livestreaming the events via Facebook. There may be some delaying tactics employed for anything with certain intensities of violence.
People won’t like it. Facebook without tight regulations has the most appeal and the most potential for dissuse.
It’s helpful when the perps offer convicting evidence that would inflame a jury’s passion for quick, effective justice.