I ask my kids, would you rather be right or happy? I don't get too excited if somebody does't agree with me anymore. Anything I contribute is either opinion or based on my research, feel free to do your own.
I believe the etiquette should be to either address the initial post or elaborate on a response. I see where people have replied to the most recent post on a topic that spreads several pages. They have not taken the time to read through the entire post prior to doing so. Ever walk into a conversation like that?
I also have to realize, written communication does have a perceived tone. Sometimes, it does not come across as intended. Some people take great exception to this and pile on quickly.
In the end, the original post is worthless. It devolves into an argument, and with greater frequency, the original poster does not come back to reply on what they ultimately did.