Even if you believe that they are useful, you're also not going to wind up as a hero in the history books. And so people wind up acting in the same way.

Besides, the argument that all of the bad ideas contributed to discovering the right one, is as strong as the empirical argument that white chairs are evidence that all ravens are black. Logically you're right. Discovering the right idea requires disproving all of the wrong ones. Similarly "all ravens are black" is logically the same as its contrapositive, "all non-black things are not ravens". It's just that you've just decided to focus on a search space that is so much bigger, that each data point in it becomes much less important.