- Archive Panic: 12 overall categories, with numerous fandoms in each category, meaning thousands and thousands of stories. Good luck.
- Broken Base: The arguments over stories containing "problematic" elements such as "dub-con", non-con/rape, underage sex, violence and torture, etc., and whether the site's lenient policies and tagging system lets writers create and readers consume these stories in a safe environment or if the site and the writers are making light of the subject matter. Critics feel that these stories endanger real people, while writers defend their material under "free speech" declarations, and supporters argue that the idea of someone's online writings are leading to actual rape and murder is a disingenuous morality crusade equivalent to saying violent movies and video games cause mass shootings (a notion that still hasn't entirely left the minds of some parts of the public). The argument isn't uncommon to online writing sites, but AO3's lenient policies attract these arguments in droves.
- Fandom Rivalry: The site has this with Fan Fiction Dot Net due to their differing policies with regards to certain stories. Those pro-AO3 love how there's much more freedom with what they're allowed to write without worrying that it'll be taken down. Those pro-Fanfiction.net often counter that said freedom gives a perfect example of why those rules are there in the first place.
- Misaimed Fandom:
- The tags on AO3 were initially intended for readers to filter works, characters, pairings, and triggers. However, it's very common for writers to add humorous, unique tags that apply only to that particular work and do nothing to assist with filters or searches.
- The original intention of AO3 was to give a place for fics that FanFiction.Net won't allow for one reason or another, such as MST fics or Interactive Fiction fics, without worry that they'll be taken down by mods/trolls abusing a report system. Unfortunately, this has also resulted in the archives becoming overrun with Lemon Fics, giving the place a reputation as "Adult Fan Fiction Dot Net" (there actually already is a site called AdultFanfiction.Net) or "e621's literature branch".note
YMMV / Archive of Our Own