A good part of Radio Shack's failure is also the reason behind the end of magazines like Radio TV Experimenter, Popular Electronics, Electronics Illustrated and many more: the decline in home "workbench" electronics building and experimenting.
No longer do people go to places like Radio Shack to buy resistors and capacitors and transistors and switches and other components to assemble into a doorbell chime or intercom. Everything is now on a robot assembled, wave soldered board with parts so small you can barely see them.
Radio Shack was part of the dawn of personal computing with the Trash 80, but they did not last long in the IBM standard PC world. Same with toys and games... and nearly nobody sells radios and stereos today.
Their style of technology was a window that closed, and in most areas they were no longer relevant to changing needs and lifestyles.