Here's the thing: I don't actually think any of those things. I think that fanartists are the fucking backbone of fandom. The issue is that some random person off the street who has never been in a fandom, when hearing that you write fanfic, is gonna think of what I mentioned, and when you say you draw fanart, is gonna think of what I mentioned. Like, as much as we think of fandom existing in a bubble, it really doesn't, and people are going to do stuff that they think is socially acceptable.

Also, that's a really interesting point about headcanon being like fanfics, but I would never have thought of that, and certainly no non-fandom person ever would.