It's the scale, speed, and reach that makes it a different beast. It's the difference between a party popper and a flashbang; similar principles, but completely different implications.
You're taking an overly simplified view of the power of internet speech. It's not that people are merely "offended." It's that an individual can be on the wrong end of an internet mob for which there's no accountability. By your standards, swatting is a perfectly acceptable outcome as long as the victim had the opportunity to mute their harrassers. Likewise, poisoning someone's reputation and making them unemployable is fine too. It's just words, right?