I usually do .. I love rope halters. However, just like any other thing, rope halters can be misused.
Since you said she was ridden in a hard bit for most of her life and she won't respond to the rope halter, that means that the bit was used to steer and control her, rather than the persons body. So therefore it is the riders fault she doesn't respond to the bit. She needs to go back to the basics and teach the horse to respond to her seat aids.
“Good things come to those who wait… greater things come to those who get off their ass and do anything to make it happen.” - Unknown