If you've ever spent ten minutes on a social media site, you get very well acquainted with "argumentative" discourse in a hurry. It seems that's all some people do. But it does illustrate the genre very well.
Sadly, I think social media sites, texting and the like have truly damaged written discourse. Or perhaps, it's just another variation on it. Still, I've noticed a real difference in people's ability to write clearly since the advent of textese.
I'm just an English major, though, and I'm a little protective of my mother tongue and a whole lot suspicious of those who try to subvert good, standard usage.