Actually, the "100,000th" post is the 116,293th post, as you can easily see from the link itself.
Some posts were deleted by the posters themselves, some by the moderators (notably during the
great spam-wars).
And a lot of posts were lost, because in some of the forums the phpBB-software was originally set to auto-delete everything older than twelve or 24 months. When we noticed and changed the setting, many threads were gone forever, especially in this very Outworld-forum, but in the others as well. You may notice that—while the boards were started on
May 21st, 2004—the oldest surviving posts in Outworld are from
March 2007, which means that about three years of conversation about outlandish topics have been lost. (Only polls seemed to be exempt, therefore the oldest three theads in this forum are polls from 2005 and 2006). There is
a thread about that as well, of course.