Funny! I was emailing with a co-worker this morning and told him about the time my Great Aunt sent me a postcard from Venice. She said there was "some band" playing in the square and they watched from their balcony. It was Pink Floyd.
If you were a successful music artist from the 50s and early 60s - you just needed a catchy tune.
If you were one from the mid-60s to the very early 80s - you needed to be able to write a good song but you usually didn't need a great voice.
There were of course exceptions - Freddy Mercury of course, who I still think had the best voice in the modern rock era - but you didn't have to sing great to be a success. James Taylor had a mediocre voice but wrote and played his own stuff - Neil Young, Bob Dylan, Bruce Springsteen - they can barely sing, but they're otherwise talented.
By the time the late 80s and 90s hit, unless you were a local phenomenon, your success is largely created. We've had people with truly unbelievable singing talent - Whitney Houston e.g. - but they're creations. They're crafted for your entertainment.
Beyonce was created - Destiny's Child was MADE.
Nowadays with the advent of YouTubers, people with zero talent can spring into fame - although I've always been amused by the fact that with so many reality singing competitions, so very few of them have achieved notoriety. Please - there have been a few. But only a few. Thousands have crossed our screens.