I always thought vocal collaborations make more sense, like singing a song in a choir. If you take just 10 people it already sounds like a choir. Here in Russia, we have a group that sings songs of famous Russian singer-songwriters (amazing, amazing songs by the way, I grew up on those), with just a few guitars and a double bass, and 10-15 singers. But it gives each song a unique vibe like it's really people's song now and bigger than any person.
Anyway, it depends on the song, need to brainstorm it. Everything's possible!