Most users like to avoid writing such short posts for fear of being classified as one-liners. That's posters whose posts hardy cross two lines. Again, those who write lengthy posts most times do that to meet up word and character requirement for their signature campaigns. It's not as if their intention is didactic in anyway.

On the whole, I don't like reading lengthy posts except the posts are the OP or the posters are good at making their narrative page turners.