Spotify has 215m users. I’d assume that is more than the group that used to download MP3s and burn CDs (which would require some technical knowhow and a CD burner).
You're seriously exaggerating. In the past, almost everyone had a CD-burner. You could use just a couple of clear as day GUI programs, a dozen of clicks and one drag and drop to download an album and burn a CD. Eleven year olds were doing it no problem.
iTunes was the most popular music source by 2007 and had built in CD burning capabilities. You created a playlist and hit “burn”. Almost every computer came with a CD burner between around 2000-2010.
Apple music is available in another 59 countries that Spotify is not.
It's not like Spotify has some insurmountable specs to run or is only available on iOS. I have it running in Manjaro, and its catalog is far more extensive than what I could have found on SoulSeek or DC++ back in the day.