Just for the record, after e-mail conversation with Sam it turnes out the site did not accept <p> on its own.
This is intentional. I wanted to make the site XHTML compilant and among other things it requires to close every paragraph with </p>
This of course make it less userfriendly so I might add some guessing mechanism and if people forget to close their paragraphs I will do that for them.
Any idea how to do that ?