Perhaps computer resources are cheaper than developer time spent on optimizations.
My MacBook Pro M1 16" seems to be averaging about 13 watts of power, about the same as previous i7. My house idles at around 200 watts (lots of smart devices, etc). Hardly worth obsessing over it.
How many users does Spotify have? Multiply that by the 79GB mentioned above. Is it still cheaper?
If a user doesn't have enough ram to use Spotify, Spotify doesn't care. That user canceling their service is lost in the normal user churn. Spotify most likely has no idea and doesn't care if resource wastage affects their customers. It isn't an immediate first-order impact on their bottom line so it doesn't matter