No, that would not work. You would also need a page=xx parameter in the URL (which will vary depending on all sorts of things... user's personal settings, permissions of the user logged in (can they see moderated or deleted posts), etc... The user specific true URL can be calculated, but it's not worth the overhead of adding extra SQL queries when viewing the thread. Instead, the extra queries/calculation is done only when it's needed (after someone clicks the link).