One other possible difference is that, at least for a time, the subject matter itself was getting easier to learn. For instance the inventors of programming languages have tried to figure out what makes a language good for teaching. (I studied Pascal, which originated as a teaching language).

For electronic components, "easy to learn" meant things like designing op amps and logic chips that behaved more like their textbook symbolic representations without weird tricks and pitfalls.

In contrast, you can't change electromagnetics just because you want something that's easier to learn. Nature won't approve. Progress has been made towards explaining it better, for instance, today's notation is simpler than what Maxwell had to grapple with. But such progress comes slowly.