I think its lack in confidence so they play it by being mysterious. Weeknd did the same, people think it was because they were just trying to be dark and mysterious, i think that was a small part of it but he just wasnt confident in his look. He's said that a lot after.

PARTY's personality on record versus personality on camera isnt the same. He doesn't come off as confident. Look at Bryson, doing the same sound. He's a lot more marketable even tho he has a quiet confidence about him. He also had a look that was easier to sell, its a huge reason why he did so well this year.