Fanfic as in writing something homebrew for a pre-established franchise e.g. the Harry Potter setting? That always seemed pretty niche to me.
I'm planning on running a class on Fanfiction writing soon online, and one of the things I want to point out in that class is that "Fan Fiction" is
old and popular
Just for a few rapid-fire examples
Dante's Divine Comedy is a Fan Fiction. Dante puts himself into the shoes of the protagonist, and a large part of the work is exploring an established canon and living out fantasies (like putting all the Pope's in Hell except the ones he liked)
The Book of Enoch is an ancient, non-canonical set of biblical stories, focused on a minor biblical character (Enoch) and his adventurers.
Wicked I was just reminded of recently, and it is also basically a fan fic, writing in the setting of Oz, but changing the script.
And, if you really start digging into it, you start wondering, what is the difference between the person who writes a new adventure for the Harry Potter Universe and someone who reboots and re-imagines a popular TV show? Why isn't Fantastic Beasts, which is about the author of a book mentioned in the HP series, basically Fan Fiction. I do believe it was written by fans, not by Rowling.
At the end of the day, the art form is huge, it is just that some people do it as amateurs and others professionally with licensing deals (or not if they are working with a public domain property)
I think you're defining 'fanfic' much differently than I am. I see it as, for example, writing a short story about Lucius Malfoy's upbringing in the Harry Potter setting - the author is using the pre-established and well-known setting wholesale and just adding some more fiction on top of what already exists...and often inserting a version of self in there as well. And it's single-author written work, and almost always amateur (I don't count the extended-universe Star Wars novels e.g. works by Timothy Zahn as fanfic). A narrow definition.
You seem to be suggesting fanfic covers almost every type of post-original storymaking, a much wider (and thus perhaps less useful) definition.
Put another way, just because Ed Greenwood invented Forgotten Realms doesn't define every game played in that setting as FR fanfic.
I also don't connect being invested in one's character during gameplay as having anything to do with fanfic. But if you're then going home and writing stories about that character, now you're into a form of fanfic I suppose, except there's no well-known franchise or setting to pin it to.
I get your objection to the wider definition. And I agree it ends up so broad it makes me wonder if it is worth defining.
But, your definition is also far too small.
There is a series I've followed called "The Golden Empire" which takes place in a universe based wholesale on an anime, the lore, the magic, everything. But, the characters are new. And, more importantly I think for your definition, it is big.
It is 8 "chapters" but that covers
checks the website 919,225 words.
At nearly a million words this would be about 10 novels worth of length.
So... it is clearly based heavily off of a property the author does not own. It isn't being commercialized, and it does not take away from the original work. It is both entirely new and rooted in the original work. And while it is "amateur" in that it is not being professionally published, it is also far larger than is traditionally conceived.
A tangent, yes, but like I said, I'm gearing up to teach a class in a week, so I've been boning up