I gave a long-winded answer at the time because I had never thought about it before. But really - it's just because I've been around sf fandom long enough. Fandom is full of writers. Many are unpublished, and over the years, more of them will have their works published. Many of them are widely published and just like hanging around conventions or pubs or other sfnal social venues. They're part of the community to whatever degree each is comfortable participating in it, just as much as anyone else with a stake in the subject, whether readers, editors, translators, publishers, artists, or anyone else.
P.S. I was tempted to entitle this "science fiction authors are human beings too".