Still, I can say with some confidence that of non-spider hits on our edit pages, only about 25% result in a "submit" post afterwards. Although I think there are a lot of people who click "edit" without the idea of seriously contributing (the aforementioned spiders; people who are curious to see what will happen; people who hit edit by mistake), this still seems quite high.
No, I think it's quite plausible. I wouldn't be surprised if most people click "edit" to see what happens, and then bail out because the edit box looks completely different from the rendered article, and they think they don't have the technical knowledge to make an edit (meaning: they don't know the syntax).
Timwi