To me, this is not about fic preferences. It's about the understanding of the characters that people have.
There are other fandoms where a lot of people don't care one way or another if the characters fit the characters in canon. Fanfic becomes basically free original fic at times. (QAF fandom is actually the most canon based one I have seen.) That could be part of it although without knowing the exact fic and comment I am commenting somewhat blindly.