In an internet mob you can remain anonymous, you don't need to actually carry out any of the threats you make (others may do it for you, eg calling for somebody to be fired), and you aren't risk any of your own reputation.
I absolutely loath seeing mainstream media write about what happens on twitter/social media. It magnifies the mob far beyond reason. "Twttier in an outrage", "Internet blows up" it's just insane. Not only does it give the impression that vast majority of users on a platform are on the same side (they're not), it gives them pseudo-credibility. And unfortunately, the next step is for corporations to take them seriously.
The more I see these stories and see how social media has shaped and is shaping the 21st century, the more I wish it was never created. It was fun at first. But the dark side of humanity has been given a power it should never have had.