It's on the current Key Stage Two Spelling, Grammar and Punctuation tests so maybe it's sticking around a bit longer.
The site would loose much of its charm if the spelling, punctuation and grammar of all users suddenly became flawless.
Actually, the board would lose 50% of its posts as the users who irritatingly believe other people are more interested in reading about their correcting other peoples grammatical errors than say, football related topics, would have nothing to post about.
A lot of the confusion about English grammar is down to a misunderstanding about the language origins. When they first tried to rationalise it, they wrongly assumed it all stemmed from French/Latin, and based the rules on that, ignoring the Germanic etc. The Americans compounded the problem, looking for the original root of the words and getting it wrong in a lot of cases.