Whereas generally speaking the people writing thousands of words of fic (instead of popping out a 1k minimum and done) are doing it because it's fun for them.
Generally speaking, maybe, but it doesn't apply to everyone. I don't particularly enjoy writing assignments in exchanges. I do exchanges for the gifts and the gifts only; the writing an assignment in return is a chore. But I also want to do it well and give my recipient a fic they enjoy because I know in turn what it feels like to get a disappointing gift, so I put in work and effort. Is it fun? Not really. But if I want to get good gifts, I feel like it's my duty to give good gifts and it generally works out (both in terms of exchange karma, and in being well liked enough that people write me treats).
Re: Yuletide history
Generally speaking, maybe, but it doesn't apply to everyone. I don't particularly enjoy writing assignments in exchanges. I do exchanges for the gifts and the gifts only; the writing an assignment in return is a chore. But I also want to do it well and give my recipient a fic they enjoy because I know in turn what it feels like to get a disappointing gift, so I put in work and effort. Is it fun? Not really. But if I want to get good gifts, I feel like it's my duty to give good gifts and it generally works out (both in terms of exchange karma, and in being well liked enough that people write me treats).