I think because it is interesting in its diversity.
Some boards only want people who think exactly the same, and do not appreciate different viewpoints. They provide a community for each other, but there is no real growth as a citizen of the world, so to speak.
This board was really intimidating to me and I lurked for a long while before I joined. I now have met quite a few people from here and count many as close friends. That is such a gift, I am very grateful. (Off point I know.)
But this is the board that gets it first...that the others glean the news from. Very cool.