You are correct if you consider 15 years a long time. They bought Radio Shack in 1963, when it was a small almost bankrupt company building parts for ham and marine radios. (The name is from what the sailors called the place that housed the ships radio equipment, the radio shack.) They decided to devote time and money to it in 1975 and introduced the first Radio Shack computer, the TRS-80 in 1977. It was about that time that Tandy phased out of the leather business and into electronics and Radio Shack full time.
However, in parallel with that, they were building and selling the Tandy 1000 series which had a number of innovations in graphics and voice production as well as installing DOS in ROM for a much faster startup. Tandy made computers until 1993. Radio Shack now sells other brands and has no brand of its own.
I used to be able to find the components in a Radio Shack to build pretty much anything I wanted. Now that’s gone and Radio Shack carries nothing I can’t get from anywhere else. Sad.