I agree, it's a good thing to properly label playlists, so people know what they are expecting when they import a playlist.
As for using sheet music or iRealPro for live performance, yes, this is a different topic and everyone may have a different reason for using them or not. As for me, playing gigs with more than 20 different singers where each of them are singing in different keys, it's convenient to have a playlist for each singer in their respective keys, so I don't need to bother them asking for the key everytime. Even if I have the chord chart memorized, I just take a quick look at the chart to make sure of the key, and I'm ready to go.
But for horns/lead players, that's another story, as they need to play the head as well