It's not Holly's fault the broadcast is bad. She has nothing to work off of with how bad Boler/Thurl are. Plus, it really ducks up the flow when someone says something that is objectively wrong and then everyone else has to adjust and act like what that person said makes sense, which Thurl and Boler do CONSTANTLY. Idk how many times Boler had said some clearly wrong thing then everyone else is like in that awkward spot of deciding whether to correct him and make the broadcast clunky/awkward or just adjust on the fly and act like it made sense.
I don't get complaining about her voice. Overall I think the voice thing is mostly something people place blame on when they don't like someone. Maybe it's something they can't pinpoint themselves so they place it on the most front and center thing.