I grew up in the UK in the 80's, and that entire generation received our music taste from BBC Radio 1. Literally the entire population of UK teens listened to that one station for ~20 years (though individuals would listen to different shows - John Peel's famous indie/punk/whatever show in the evenings was very different to the daytime mainstream stuff).

In Australia it was ABC's Triple J - similar story. Everyone tuned in to the annual top 100 tracks of the year.

That reach has not happened since with any media that I'm aware of. It was very unifying - we were all aware of the same songs, even if we didn't like the same songs. I can sing along to Duran Duran even though I was very scathing of them at the time, in part because I was force-fed Duran Duran every day on the radio.