However, the example you give is dark humor, so you win me over there.
Q: How do you rank yourself among writers (living) and of the immediate past?
Nabokov: I often think there should exist a special typographical sign for a smile – some sort of concave mark, a supine round bracket, which I would now like to trace in reply to your question.
And even the best writers, when writing quickly in an immediate medium like the internet, can get it wrong.
I think that is the key; when interacting socially there is no need to make sure your writing is top notch and expresses your emotions adequately. You just stick a smilie on :)
Consider a real-life conversation. You wouldn't pause for several minutes to make sure the next sentence properly conveyed what you wanted to say. But you might smile and wink at the end of a put-down to show it was a joke.