Labels can release compilation albums on Spotify.
Even if the releasing label doesn’t have streaming rights for some songs, they might still show in the compilation due to track-linking.
Track-linking replaces unavailable tracks with an identical version that has streaming rights. The compilation plays as normal, but royalties get paid to the rights holder instead of the compilation label.
Compilations with 4 or more artists show the artist name Various artists. They show in the Appears On section of the artists’ profiles.