Nothing was considered more solid 'immutable' than classical physics, which had far more direct empirical evidence, measurement, observation, testing and was considered unquestionable among academia for longer than evolution. And as with evolution, it's simplicity, elegance, was very attractive, along with the explicit implications of such a 'complete explanation' making God redundant.
While outside of the academic minority, most people believed the world they observed around them was just too complex, beautiful, functional to be governed by a few simple laws, and they were absolutely right.
I think 'classical' evolution as is, fundamentally fails to account for life for the same reason, in a word- entropy, simple laws produce simple results.