Perhaps it's simply a matter of people feeling unworthy... as if they don't deserve the attention... others have more serious problems... that sort of thing. Often too, I think, where you tend to see this is at the beginning of posts written by members who are still very new. So there is perhaps also an element of shyness about it as well. It is true, though, as Travelinglady mentions, that posts that really are long tend to attract fewer readers.