...

Not to mention medical drama based fandoms, sitcom based fandoms, and so on.

I don't doubt that such fandoms exist, but they are probably peripheral compared to the SF/fantasy scene. We have several magazines catering for telefantasy fans

Actually, we are probably fewer in number than the Soap Opera fans, I would guess. They have websites, more magazines than we do, or at least easier to find. They do write fanfic. (I have not looked into this matter personally, just read about it. Only soap opera I ever watched was Dark Shadows)