It doesn't on the internet. It's just a cheap dig, to dullen points, when a logical counter point can't be made. That, and it's for kids to attempt to "look cool" in front of their community of choice. I remember this same type of behavior was displayed every day in high school, with people constantly making fun of people. Grammar, spelling, etc. doesn't really matter on the internet, as long as people can figure out what you're trying to say. And nornally when they're acting like they can't, it's an issue with the said person's critical thinking skill.