ELI5: why would a lesser known version of a song have lore plays on Spotify?

For example, the acoustic version of ‘the sound of silence’ by Simon and garfunkel is far less known than the major 60s hit by the same artists with added drums and electric guitars…

yet the acoustic version has 650m plays vs 40m for the hit.

I see this often that the mainstream hit is buried under a lesser known version. What’s happening for this to be the case?

Edit title: more plays