Along with the Editor's Note: I am not sure about the general trend of how much teaching was required from graduate students and post docs over the last hundred years, but I know that it is very difficult to be both under the pressure of teaching multiple classes in order to be paid and of publishing papers in order to get hired in the future. This much stress definitely hinders the quality of the work, and it is easily possible that many researchers come to their best ideas when they are significantly older and in a stable position.
Not only that, but it's also the way of thinking characteristic to novel ideas. Technology helps you to get more advanced things done with less effort.But the beauty of good research in science is not technology, but simplistic elegance. For that you have deep your field, which takes time.