I think it's more lack of internet forum experience.

In every day speech, you don't have a Google reference, so you typically ask others, as opposed to trawling through books.
As for those who also post retardedly liek dis den » as above but too much MSN?
As for those that just don't get a hint after being told, then it would probably be just a fail person.  I mean, the average 10 year old seems to be more intelligent than these people...