While I see that being kinda true for THIS site (still hoping for one of the many MLP FoE FoU fans to pop up), it's FAR from totally true.
This was once a mod to Fo3, and is now it's own standalone game.
This is a game made from scratch.
This is one of many pnp/tabletop games.
This is a Fo2 mod.
(I once found a database for the fanfic spinoffs of fanfic FoE, and can't find it now for some reason.)EDIT2: I found it just now.
Here
This is a different database. This one if for almost anything made by fans. Not so much fanfictions of the fanfic. (look into comics and you'll see some people trying to make Kkat's original into a comic and one person is doing it all by hand. That's over a thousand pages, being turned into a graphic novel.)
So this makes me think (along with this thread being here to begin with) that there has to be more than just one brony (me) on this site, or will be in the future.
EDIT:
I forgot to mention the hundreds of diffrent people reading the stories on YT, that a group working out how many words ALL spinoffs + original have (with it not being update, it's over 10 million words), and the number of spinoffs is over 500. On youtube, there's four groups doing unique things (one's a radio play of FoE, another is working on making it an animated series, another on a radio series of a guy looking to set the world right or at least record the events going on, and another radio play of a paddler who took on a too big to deal to escort another pony safely.) Sooo, yeah, a lot of people have a big interest in Fallout: Equestria. lol