Radio dominated the first half of the 20th century but the advent of affordable TV sets in the 1950s seemed to spell doom for the format. Yet, radio endured. Radio was able to create a distinct image for itself, separate from TV. I have own theories as to why (cars, transistor radios and the music industry) but nothing conclusive.
TVs weren’t portable.
But even today audio-only formats survive, maybe not as radio but as podcasts. Also cars, where you still
can’tshouldn’t watch a video while driving.