Having conversations with random people on the internet is interesting to say the least. You don't know who you're talking to, what they look like, or most times, any background information on them, and then suddenly you're locked into a conversation where you may not know their motives or where their opinions are coming from, and it can often lead to conversations that are misinterpreted, often times argumentative, strange, seemingly coming from left field, but sometimes, clear, concise, and understandable even if you disagree with what is being said.
Some people believe in the context of such conversations, there is "no line," even if outside this box, they know there is one. They often think a person should be allowed to say what they want because "it's just the internet," but I think there is a line. I recall a few months back having a conversation with someone and we were talking back and forth and someone entered into our conversation civilly at first, but then they just started attacking the other person for no reason.
Before I could even block, they were quite literally eliminated from GaG altogether. To me, there is a line where we're no longer having a conversation. It's when someone takes a subject matter and either because they are trolling or just acting like jerks, they take it beyond that subject and attempt to make it nasty and personal (without knowing the other person, mind you) or they simply stoop to hurling insults because they can't defend their own position.
It's debate 101. You should be able to state your position and back it up. If all you can do is say, "you're stupid," and continue slipping further and further into the hall of insults, what would lead me or anyone else, to think that person has anything of any value to say today, tomorrow, or any other time we should happen to interact? And when you take it beyond to using four letter words or insulting someone's gender, religion, sexuality, race, or abilities with phrases that would make any mother blush, it's a block.
If we want to have community, we should be able to share in that community and talk to one another like we would as if the other person were standing right in front of us. We shouldn't block people because they simply civilly disagree with us or say something to the left or right of our own opinions. We are here to share our opinions and exchange information, and part of that exchange is being able to communicate our thoughts and ideas effectively with others in a civil way.