Oh, all the time..
There was this guy, Josh Pillault, a senior in high school at the time, who was playing Runescape, he ran into another kid. They were both being edgelords, going back and forth with banter. Well, Josh makes a school shooting joke. It was clearly just a tasteless joke and in the heat of the moment. Well, the kid reports him, Runescape calls the police (or the kid called the police, my mind is a little foggy on that since it's been a while.) Josh gets sent to federal prison for 5 years. Teachers were willing to vouch on Josh's behalf, saying he was a good kid, there were no weapons in his home, psychiatrists deemed him mentally stable. It seemed like the judge just wanted to make an example out of him. I made a video talking about how I was disgusted with the legal system, telling my audience to go and subscribe to his YouTube channel (He's now over 10k subscribers and plans on making videos in February when he's fully released and able to, so actually an even bigger YouTuber than I am) Josh saw my video, it seemed like he really appreciated the support I was showing, and we had a heart-to-heart conversation in the comments.
Another big example I have is not so positive. One was on another YouTube with more subs than me, who has a reputation for being a troll, doxxer, neo-nazi, etc. I never knew about the criminal behavior until I got invested into his community. The first video I did on him was just a reaction video. He made a video of him in his laundry room threatening to beat someone up. He responds back, trying to dox me (failing horribly, because I'm smart about my personal information), hurling a barrage of racial remarks, a lot of trash talk. And then I made another video, which was a full on exposed video that I researched and spent time on, putting the guy in his place.
I got a lot more, but you get the point. I think all that matters is, if you're going to rant about someone, make sure what you're saying is true and make sure there's actually a point behind it. Whether it to be to entertain, or give constructive criticism, or inform the public, or whatever. If you can't back up what you say, there is always the risk of a libel suit, which some people are more than willing to pursue. Honesty is also important. People appreciate it if you don't sugarcoat things or give selective treatment, just overall fairness. And be wary about being hypocritical. If you criticize someone for doing something you do, it doesn't ruin the argument, but it takes away your credibility, which is important for a YouTuber.
