Twitter is a crowded bar. Most of the people who are there, are there to relax, hang out and chat with the friends or colleagues they showed up with.
Twitter is a crowded bar. You're having conversations in a public place. You are surrounded by people having conversations within your earshot. But none of that makes what you are doing or what they are doing "public debate" by any reasonable definition.
Twitter is a crowded bar, not an alternate universe, so try not to say anything that would get you in trouble if it was repeated outside the bar.
Twitter is a crowded bar. Sometimes you run into people you know. And if they're cool with the friends you went to the bar with, everything will be cool.
Twitter is a crowded bar. Some of the people there are being paid to promote a product. Some are there to network. Some are there because they're famous and it's a "place to be seen". You can hang around them if that's your thing, but they're at the bar because everybody else makes it worth them being there, not the other way around.
Twitter is a crowded bar. People can go to bars to meet strangers, to meet new people in a new town, or because they know it's where other people "like them" hang out. But it's never anyone else's responsibility to make sure a stranger feels welcome with them personally, or with their social circle.
Twitter is a crowded bar. If you hear something interesting from a nearby conversation there's nothing stopping you introducing yourself and joining in. But again, it's your job to make sure you're not an unwelcome interruption.
Twitter is a crowded bar. If you're that person who always ends up cornering a stranger who doesn't particularly want to talk to you in a one-on-one conversation, you're not fooling anyone.
Twitter is a crowded bar. If someone says "I didn't come here to argue with you about that", even if it's something they brought up in the first place, you should probably find another conversation. There's plenty of them around.
Twitter is a crowded bar. If you go there to pick fights with strangers, you're an asshole.
Twitter is a crowded bar, but they've kind of skimped on hiring bouncers.