I can't access LiveJournal from work, so I'll check it out when I get home, however:
not sure how exactly 'more' works on WP
The more tag tells the engine where the stopping point is when you're looking at the main index page.
Usually, your main index has a bunch of posts on it. If you select one of those posts, you go to a page with just that post, and potentially a place to add a comment and such. The more tag causes a post to stop there on the main index and display a "read more" type of link which, when clicked, takes you to the individual post page.
Which is why it doesn't make any particular sense for it to be an "enclosing" type of thing, since it's just a marker. It tells the main page where to stop displaying the post, and it does nothing on the individual post pages.