Darwin made a wonderful move in this game: he offered a mechanistic explanation for the apparent finalism of the life forms. The differential reproduction of slight variations in traits, spontaneously produced one generation after the other, followed by the filter of natural selection, did the trick. It was all the teleology we needed, but based on a perfectly mechanistic process. This idea looked unbeatable. Immediately, applications of it were discovered in the diffusion of goods, in the financial markets, in the spread of fashions, songs, tunes, even scientific hypothesis. It was a smashing success.
Moreover, it’s a clever idea, not something obvious, not the kind of idea that everyone discovers spontaneously. Teach it to a class of kids, and they will realise that it never occurred to them beforehand, but that it’s so damn clever. They feel so damn clever just for grasping it. This is, I think, crucial. Adults also feel clever for just grasping it, and for developing on the spot an intuition of zillions of examples and applications.
I would submit that a lot of people feel "so damned clever" for grasping it, because they are told that it really is some sort of advanced form of thought, when in actuality it doesn't go in any essentials much beyond what the philosopher/poet Lucretius wrote more than two thousand years ago. As David Berlinski points out, it is the mere work of an afternoon to understand the idea, and one needn't be particularly clever at all to grasp it.