They should have never used random builds from random people. This should have been more thought out - it should have been specific dev builds that had specific synergy (so it doesn't have to be meta builds, but builds that worked if it was thought out) and the time completed should have be a set time. It should have all been planned out and not random.
The Devs should have made the challenge, not just pick some random crap build that may or may not work. It should have been fun to play with. The devs should have made a build that other players may have not used or had a synergy that most people didn't see.