Well we don't even allow markdown in our editor. We do this to prevent people from turning normal 240 character post into 1000 words post on zappl.
Its a preventative measure against abuse, zappl is meant to host zappl data and when you edit data it messes with the filter method of only showing zappl content. Once app:"name" changes which it does when you edit a post.
We will look into how spaces and breaks are handled in the code on post to insure the quality of how you wrote the zap. Also as sames said we will be adding editing features soon to allow people to fix their posts.
There could be a second box for people to go in depth for other platforms. The main zappl post will be the TLDR. Not sure how well that would work out personally but just a thought.