Certainly the Shinigami thought that what the Quincy were doing would destroy the world. So based on that information, the answer has to be yes. However, since the Quincy were exterminated - it's a moot point as we really don't now how the world would have turned out had the Quincy been left unchecked. For all we know, the Quincy would have self corrected once it became apparent that their actions were breaking down the birth-death-rebirth cycle.