> But it can change the meaning. For instance, if I write a tweet that says "I like the joker character" and twitter appends my tweet saying "People that like joker might shoot up a movie theater", you've changed the intent and meaning completely from what was intended...

So? No one has a "right to the last word," so that when they speak, everyone else has to shut up so their words will be the exclusive influence on their audience.

It's important for free speech that people be able to point out when someone has lied or spread misinformation.