Yeah, some people do actually.
I've seen low levels do better, score (damage, healing, etc) and objective wise the higher level players.
Either cause those higher levels aren't trying or just bad players. That's a different argument, but I don't see the point in creating more brackets for WZ.
The only problem I see is that some classes at level 10 don't have their stun yet. If players got a stun and their CC break skill, I think they're good to go for WZ.
I suppose if more then half of a team is comprised of people under level 20, that would be a problem. Been there myself, not often, but been there and we never win.