[bdbenton]

It's often in retrospect as well. It can take time for the impact of certain innovations to unfold, and it often begins with a small group of people. The breadth of human innovation is now so wide that a scientist/engineer from the 1950s simply doesn't have the same scope of problems and areas of study to work on.

That's why people like Leonardo da Vinci could exist, the scope of human understanding was much smaller and so their work was much more wide-reaching and foundational. Today, you can dedicate your life's work to some hyper-specific problem in a very specific field. Tomorrow, this work might seem fundamentally primitive or foundational in the way that previous generations are perceived.