I think a lot the issues you brought up were already addressed by b00daw in his initial description. It's not only an option to give people a chance to try something new, but a different take on anonymous submissions in general.
Zero: "how exactly is a system that rewards people when they single out which tracks are which, based on composition style at the cost of the artists who submit them, going to help artists break free of their "expected styles" in the first place? "
b00daw: "to give someone who has already established an identity the chance to remove the associated expectations. Sometimes well-known BotBrs here use alternate identities to explore different styles. This could effectively squash the purpose of having alternate identities while adding funfactor to guessing who made the mystery tracks"
And 'funfactor' being the key word here. Reading between the lines, I appreciate b00daw's idea for quietly stating, "Simple anonymous entries aren't good enough for BotB, it needs to be a little more original and fun."