Who Is the "Fringe Group" Behind the Yosemite Suit?

The other day I talked about an Associated Press story that wondered aloud how the so far successful lawsuit over management of the Yosemite Valley might impact the rest of the national park system. In that story, Yosemite spokesman Scott Gediman referred to the Friends of Yosemite Valley as a "fringe group."
Who is this fringe group? How did it succeed when higher profile groups such as the National Parks Conservation Association decided not to get involved in contesting the Park Service's development vision for the Yosemite Valley?
You can find some insights into the Friends of Yosemite Valley in this story that Mark Grossi wrote for the Fresno Bee.