I actually thought some about that question. I dont' do that stuff anymore, so why not?
I think it has to do with the mistakened notion that people are willing to change their opinions based on logic and reason. They certainly are not, and that was a late revelation to me. I have almost always approached life from the perspective of "if I am wrong, then I should be able to just 'see' it and acknowledge my error....., and why would I not want to do that?" I assumed others do so, and that is both a bad mistake on my part and a bad judgment on how men reason in general. (I have no idea, after 38 years of marriage, how women reason, so I won't even go there).
It took me years of stupidly banging my head against a wall to come to the "EUREKA!" moment of realizing that men choose ideas, groups, visions, sides, etc NOT AT ALL based on intellectual, cognitive or rational bases. They choose sides in a debate based on other, deeper and less analyzable motives, and then go looking for rational constructs to defend them. This seems so obvious to me now that I feel like a total moron for not seeing it before. What is more, the men most vocal in defending rationality, reason, intellect and cognitive process are often the most blind to their own NONintellectual prejudices.
For this reason, I would go back and make the same arguments, dreaming that just making them "pretty" or nice and civil and gentle and kind (or the closest someone like me can come to that)....., and that people would agree to dismiss their prejudices. Instead, I was puzzled and frustrated that they would, politely and civilly (lol), hold on to the same basket of nonsense, often more fiercely than before.
When you don't understand that the reason for someone's illogical, dumb idiocy has NOTHING to do with their reasoning process, then you just marshall your arguments, detail them out and apply more force. This leads to ..... ahhhhh, "friction" would be a polite word for it.
Being older and, in some rare areas, a bit wiser, I see that it really is wasted time. It is not that some really really stupid stuff should not be openly mocked and ridiculed. It should (and of course, I try to do my part
), but I have very very very rarely seen someone in open debate change his/her mind. I have, though, heard from lurkers, hanger ons, and observers that the structure of the argument either affected them, changed them, or strengthened them. Nowadays, when dealing with issues online, I try to keep in mind that the person with whom I am talking has (usually) very little interest in whether what either of us is arguing is true (there are notable exceptions to this, of course). You are really playing to the gallery.
That is the biggest reason I don't go back over and over any more, and yes, I do feel profoundly stupid for being unaware of this earlier in life.