On June 2, 2012, the popular fanfiction archive FanFiction.net posted this notice on the front page of their site:
"Please note we would like to clarify the content policy we have in place since 2002. FanFiction.Net follows the Fiction Rating system ranging from Fiction K to Fiction M. Although Fiction Ratings goes up to Fiction MA, FanFiction.Net since 2002 has not allowed Fiction MA rated content which can contain adult/explicit content on the site. FanFiction.Net only accepts content in the Fiction K through Fiction M range. Fiction M can contain adult language, themes and suggestions. Detailed descriptions of physical interaction of sexual or violent nature is considered Fiction MA and has not been allowed on the site since 2002."
On the same day, tens of thousands of works were lost due to this policy suddenly being placed into effect. It is very unlikely the majority of these works will ever be recovered considering fanfiction.net has a robots.txt page keeping resources like the Internet Archive out.
It is very likely that because of this incident, someone decided to try to save all of fanfiction.net into an archive that was well over 100GB and posted it on the Internet Archive.