There is no such thing as magic. Most of electrical engineering was invented by 1925, reduced to practice by 1935, and mathematically analyzed and scientifically understood by 1945. The last bit was finished by 1965. Since then there has been only a minor trickle.
It is the changes in government regulations and the lowered costs provided by the large engineering efforts put into improvements in manufacturing efficiencies that have caused the wide spread use of electronic items.
Here are examples. Phase locking of oscillators was mathematically understood by 1650. The FFT goes back several hundred years. Feedback control systems were patented by James Watt in 1788 and the Routh stability test was published in 1884. Waveguides were mathematically analyzed and understood by 1880. Frequency hopping spread spectrum was a commonly known concept by 1917. By 1900 DSP was well developed and even the z to the integer exponent notation was in use. Digital computers were mathematically understood by 1800 and reduced to practice by 1943.