And what do you mean "failed"? Like these guys? http://itasoftware.com/careers/hiringpuzzles.html I wouldn't mind "failing" like them.
I heard you can feed a family of four on a technical challenge for a year!
You go find 100 people in 100 companies with rockstar performance, excluding those that are still in university (graduate or undergrad), and you wont find 2 of the 100 that will stop and fill out a test.
You want good people? Hit your networks or find someone with a netowrk, and find someone who is busy and well respected in whatever he or she does. Good people are working right now, not trolling job boards with time to take tests.
There is a time for tests and puzzles: in the interview process. At this point her or she understands the role and the team, and now you want to know how (s)he thinks, and if the culture is right. Throw the toughest you got at that point, but on a web form? Thats a great way to attract B & C talent, in my opinion.
Also the team is very well-respected (previously at Facebook) and I think A LOT of people would love to work and learn from them. Maybe even for free for a limited time.