Does anyone know why people on the internet (Answers, blogs, etc.) can't spell or type?

OK, so i'm 67 and a former professional proofreader. But I notice how many people can't spell, type, or compose a complete, coherent sentence. At least on Yahoo, they do try to use *** instead of the swear words and insults, but there's still a lot of insults tossed around. Let us allow the other person the right to be a complete idiot without having to be rude about it. After all, someone may think YOU are a complete idiot, too. You don't live as long as I have without having been there once or twice. (3 marriages down, 2 trips to prison, yeah, I do "idiot" real good.)