Stephen Stills is one of the other major members of Young's supergroup, Crosby Stills Nash & Young, and Stephen Stills currently is listed as having 286,696 monthly listeners on Spotify.

Gola Gianni is a random rapper that I have never heard of before searching the word "mumblecore" on Spotify just 5 minutes ago, and he has 328,039 monthly listeners listed on Spotify.

I think you're both severely overestimating how many people are actually listening to a lot of these "classic" artists and also severely underestimating how popular random flash-in-the-pan artists are on Spotify.

edit: I didn't specifically use Young's monthly listeners right now because I suspect the news-worthy nature of his absence and then eventual return likely has temporarily inflated his numbers with the additional attention on him

2nd edit: I kept being curious so I kept looking at numbers for other "big name" bands.... I find it almost unbelievable that there is still apparently over 22 million people listening to Aerosmith monthly. I don't hate Aerosmith, but I'm not sure I could even sit through a whole album of theirs, so that 22 mil is breaking my brain.