My theory (not rocket science):
If someone else's playlist includes a song or artists that I like, there is a good change that I will enjoy the rest of their playlist.
Currently, you can only search for public playlists via playlist name. Considering that most people do not name their playlists to accurately reflect the type of music it contains, I believe that the current search functionality is quite limited.
Spotify should have functionality to search for public playlists that contain a song/artist. I think would be immensly helpful for music discovery.
Best of luck,
P.S. - Down the line, it would be interesting to see "similarity scores" between two playlists. Could be quite interesting for finding new music.
Updated on 2017-10-25
Hey folks, we wanted to revisit this idea as it has received a lot of votes from you. We are definitely looking at some improvements to search for 2018, but this exact feature is still not on our current roadmap. Please rest assured we've raised this idea and the votes with the teams behind Search. They're aware of your feedback and will let us know if anything changes around this. Thank you for continuing to bring your ideas to the Community Exchange!