For example, in your analogy, they're not being manhandled out of the venue. Someone at the venue is taking their picture and following them home, distributing that information, then random people are showing up at their house for the next eighteen months or more. Then people are showing up at their family's house with threats, and their boss's house demanding that they be fired.
Is this the type of "shit [flying]" that you think people should be prepared to expect when they post things online?
(Btw yes, that sort of reactionary persecution can happen and does indeed happen in all sorts of places. It's part and parcel of meaningful political activism anywhere in the world.)
Why should the consequences be so completely out of proportion to what was originally said? "In public" covers more situations than it used to, and the size of your audience isn't always intuitive.
> Can I walk around Harlem with a racist sign without expecting to be roughed up at some point?
Probably not. Will you be roughed up by thousands, be followed home, and be stalked and harassed for years? Probably not.
The fact that "in public" situations might have expanded (and sometimes replaced more private ones) is a problem that can (and should) be fixed with education. NBD.
Just because some people seem unable to comprehend the (massive) scale of internet space, it doesn't mean that we can magically make it a paradise where real-world behaviour honed in thousands of years simply does not happen. Internet space is a new all-encompassing dimension, the scale of which we've never seen. One should think carefully before acting in such an environment. It's not like interacting with press or peers in a given niche; it's like broadcasting on all channels in all countries at all hours. The chances of getting reactions you might not like are higher than with any other media or venue; but on the positive side, the chances of getting reactions you will like are also disproportionately higher than anywhere else. Continuously complaining that the glass is half empty will just provoke someone in smashing the glass to solve the problem -- because "you didn't like it much anyway, always complaining".