I agree with OP I freely admit I'm not the worlds best speller and in this informal environment is it really nessasary to point out mistakes? It does seem like some people are a bit OCD about it tbh
It's not OCD, it's a nerd mentality, I'm not saying that OcUK forums is full of nerds because tbh I don't believe it is,
but, your certainly going to find a higher concentration of them on here than most places, and nerds as a whole seem to have this annoying personality trait that involves them correcting you on every mistake @ an almost pedantic level, even though they understand perfectly what you was trying to convey or do.
Why they do this I'm not sure, I'd hazard a guess that it makes them feel good pointing out other peoples mistakes because their own lives are void of any other 'normal' pleasures so they suckle off the energy they get from putting other people down.
Unless someone is complaining about text speak (which I think has no place on any forum) I just think they are very sad individuals.