Back in the day, a hobbyist with just an elementary education in electronics could build/repair a radio/receiver with a soldering iron, solder sucker, and multimeter. The really top notch guy had a signal generator and a scope. RS was the source for all the parts you might need. We installed many a car stereo w/ parts from RS.
Now circuit cards have multiple layers. Components are tiny. Schematics are complicated. The skill and equipment required are far beyond the hobbyist in most cases. And I wouldn't dream of trying to install a stereo in a car today. Demand for DIY electronics is rapidly fading.
I don't know how RS could have evolved to stay relevant... and apparently neither did they.