Of course, the risks are minimal on twitter. At worst they can write a death threat, but nobody's going to come to your house. They'll spend more time arguing with your defenders. And the attention span is short, by next week your controversy will be gone.

Contrast to getting into an extreme argument with your neighbor could result in a physical fight, destruction of property, or death.

Ultimately, this is why I really don't want to see articles on Internet discourse dominated by "culture wars" topics; So little is at stake. I highly doubt mass tweeting and public shaming will ever have much power over anyone, or change national policy or thought. However, someone once told me though that the most vicious fights are often the pettiest, so I only expect culture wars stuff to be more common in the future.