> a few hundred years ago introspection wasn't all that common

Marcus Aurelius, Napoleon, Lincoln, the founding fathers, and a long slate of writers and philosophers would like a word

You are again making the same mistake, please try to understand what I'm saying. Atheism was a known concept at least amongst some priestly class in India but that didn't matter - the larger part of the society was not developed enough to understand it.

Society only meaningfully changes when a critical mass of people understand and apply a concept - in this case introspection.