what if i have a youtube link and i want to stream on spotify? what if i have an apple music link but want to play it on a linux device where only spotify works?
it's more likely that you discovered a song on youtube and wanted to add it to your spotify playlist, rather than browsing spotify and then deciding to listen on another platform.
someone should make a service like this, but make it universal for all platforms.
however, i found the ability of matching a spotify artist profile to the artist's platform profiles impressive.