I mean Stolas' VA, who is arguably the best singer in HB, is from theater. The same goes for Blitzo who is supposedly the main character. It only makes sense to keep getting theater actors if they are the fan faves. Same goes for Ozzy as well.
There's nothing wrong with recruiting someone from the major leagues into the minors if they really want to play. Amy Lee was a professional opera singer and essentially wiped out every other female vocalist in the alternative scene(With the exception of paramore,and Imogen Heap) by just going down a rung from opera to front runner for a band.