I also have only a high school education. I'll be the first one to say that your education level has no bearing on how smart a person is. I am not better than anyone, and spelling isn't that important in the world-at-large. In fact, most of the high level managers where I work can't spell a thing by themselves. Who does it for them? Me.
That being said, when the world in question is a forum where communication is by written word, we should take the time to make sure that our posts are readable (especially by those who have more difficulty with reading and spelling) before hitting the "reply" button.
Furthermore, I did not call anyone out in particular. It is something I see here every day. The example I made is a common mistake, especially in this part of the country, where the two words sound very similar when spoken.
If someone can't make any sense of a post, how much help is it going to be?