I’m definitely not saying every playlist is a release! But that artists may use platforms/avenues (and formats etc) not meant to ‘release’ things to release things. And we should store those.
I don’t think you could write a guideline that allows platforms like Bandcamp but disallows anything released using Spotify’s playlist function. Without explicitly mentioning ‘Spotify Playlist’. If you have to explicitly disallow a channel then it’s not good criteria imo.
A broader guideline like “we don’t allow digital releases that regularly change” I think is perfectly reasonable.