I strongly disagree. My lower class sets of grandparents both had pianos. Other family members had violens, accordions, portable little organ things. Making music was the norm before the radio just like the original poster said. Do you think classic blues pianists came from rich families?
Honestly I think I just misread "before the radio" as "before the internet" and didn't realize it until it was pointed out a second time to me. I don't actually know what life was like before the radio, even my grandparents would have been too young for that.