Yes, it’s true, Warrior fans. Before the 2012-2013 season had even started, the Warriors were offered James Harden for Klay Thompson, but the they rejected the deal due to their fear of penalization of the luxury tax.
According to Bill Simmons of Grantland, the first team that the Thunder called when looking for potential suitors of James Harden was the Warriors. They had a growing interest in Klay Thompson, who was looking like he was going to have a very bright future, despite some apparent problems with his thought process. Because the Warriors rejected the trade, Harden was dealt to the Rockets.
If the Thunder would have taken players with contracts expiring in 2013 0r 2014, like Richard Jefferson and Andris Biedrins, the Warriors would have likely gone for the deal, and inserted Harden in the starting lineup, to be a deadly scorer. A lineup of Curry, Harden, Barnes, Lee, and Bogut would have been one of the most feared in the NBA; just look at what James Harden has almost single handedly done with the Rockets.
The Warriors had used their amnesty clause on Charlie Bell a couple years earlier, to make space for players to sign in the offseason. Unfortunately, they weren’t able to acquire anybody, and didn’t sign anyone else.