Lots of reasons.

1. They pay their artists an an absolute pittance with a model that vastly favours the big labels. New artists, those artists striving to establish themselves and/or independent artists are screwed over.

2. At the same time they pay hundreds of millions of dollars to pricks like Joe Rogan.

3. The ‘fake artists’ controversy where Spotify pay stock music production companies to produce pretty bland ‘playlist’ mood music, then created an internal team to seed these tracks on their uberhyped suggested playlists.

4. Getting caught heavily promoting AI Bands who have been trained on actual musicians work, without paying them for it, which in turn allows Spotify to pay out even less royalties to actual musicians.

5. Daniel Ek recently investing in 100m Euros into an AI weapons company, which has triggered an artist boycott.

6. You have zero ownership and zero access rights to the music you stream.

In short, if you care at all about music and the people who make it then streaming in general is not a good model for their future and Spotify is poison.