Re: Please could you prove that I'm wrong?
It's not about being presumptuous. It's about understanding ideas and how they relate to people's worldviews and philosophies whether they be personal or societal. Asking people to 'explain that' is akin to asking for a lecture on the history of ideas, the development of civilization, ranging from anthropology, sociology, religion, history of academia, history of philosophy, cultural zeitgeist, general history, and so on. Personally, I don't want to lecture people, nor do I think people want to hear a lecture. If the topic doesn't seem relevant to your understanding of the worldview, don't merely shrug it off saying it doesn't make sense or say that it's 'presumptuous'. Asking 'why' recursively is just asking for a series of tl;dr notes. Ideas are tied and grounded in history, they aren't standalone axioms that just 'formed' out of thin air. I think the history of Darwinism was a good example, though it's being ignored for some reason.
Ever wonder why the scientific method came about in the first place? People didn't suddenly go 'eurkea'! like Thomas Edison to come up with it. Its foundation was a developmental process, given birth by a number of pre-existing ideologies, and with a combination of cultural milieus grounded in historical events.
Evolution is tied up easily with naturalism, for one. It's in the spirit of rationalism and empiricism. Its study fueled atheism [verbal emphasis on theism], which (atheism) denies, for the most part, teleology. In short general atheism = anti-teleology. That gave rise to nihilism, which Lazuli notes. And to some extent, nihilism is the rising ontological philosophy today, which is fueled by atheism* (and postmodernism) (which again is grounded in historical events, a zeitgeist, whatever)
*the idea rather than the movement, just to clarify
tl;dr ideas -> history -> new ideas -> history -> newer ideas etc