People forget that if God didn’t want us to cure these diseases, then he wouldn’t give us minds with which to figure out what needs to be done, or the stuff we need to make the cures with.
And they also forget that Jesus was more worried about your soul than your body. Also, biblical doctrine DOES NOT teach that you will get what you want, in this case healing of their daughter, just because you pray for it and ask for it, even if you REALLY have faith it will be granted.