This. Then I just zip it up, make short posts and hope I don't get too bored. Also the intimidation factor, while I doubt I've ever really intimidated anyone, I do know the feeling of being in awe of someone else's writing and looking at my own to suddenly think it should have been written in crayon.
Effort? What Effort?
Role playing should be a give and take: if you give someone five meaty paragraphs of worthy content, you should get a similar amount of quality in return. Nothing can be more insulting than pouring your heart out in a lengthy, descriptive, well-written post you're proud of, only to receive a reply post that is a sixth of the length. It just comes off as laziness, or even rude - giving your partner the impression that the story isn't worth their time and effort.