I got curious as to when certain types of fic were banned on FFn, so I did a bit of research.
25 April 1999 - "Fanfic only" rule enforced, removing polls, questions, announcements etc
20 May 2001 - Anne Rice fanfic removed
1 April 2002 - Lists removed (they previously had their own category)
1 April 2002 - MSTs banned
7 April 2002 - Actor-fics banned
12 September 2003 - NC-17 fics banned
12 September 2002 - "Chat room or keyboard dialogue based entries" banned
6 February 2003 - Original fiction moved to FictionPress
22 March 2004 - Poetry category removed; original poetry banned
19 April 2004 - Clarification that the no-chat-dialogue rule means none at all, including author notes
30 April 2004 - "Original superheroes" category removed
27 July 2004 - Clarification that script format === chat dialogue
27 July 2004 - Clarification that CYOA and 2nd person are banned as interactive fiction
27 April 2005 - Clarification that pasting song lyrics into fic is banned
That's all I can find. Notably, I don't see any indication of when interactive fiction was banned - it may have been a founding condition of the site. Similarly, they don't ever seem to have explicitly banned song lyrics - just clarified that they already were banned.
Script format is rolled up under chat format, and banned on the simple grounds that it's usually bad. At least they're honest?