Those multiple chains were ladders; the main chain is only compromised of itself.
But why would on need chains for a mountain? 'Cause it ain't a mountain. It's just junk that fell off of Zeal!
Because they have to worry about the mountain floating away.
Because...the mountain's been...enchanted with...magical force...that allows it to defy gravity, and...
If you look at the mountain on the map, you see the mountain bobbing up and down in the sky, with the chain being tugged. The chain binds it to the ground, which is the point.