The problem with that is the special cases. Take dislexics for one. I've known a couple that post on the internet that aren't taken seriously because of the way in which they present their points, but are you really going to not listen to a dislexic's point because his spelling and grammar isn't perfect?
The other is with people who just don't know how to type. If I had never taken a typing course, I know it would be more of a pain in the ass to avoid spelling and grammar mistakes in this kind of format. I know doctors that don't have very well-typed posts on the internet, but a lot of that is because they generally leave the typing to their secretaries. I also know plenty of #####s that write very clearly on the internet. So don't write people off just due to how their thoughts are presented in one medium.
