"would have trouble making predictions. Physicists have made this criticism since the beginning." You can go one step further. If you regard string theory as a

"would have trouble making predictions. Physicists have made this criticism since the beginning." You can go one step further. If you regard string theory as an attempt to answer questions about quantum gravity, then this criticism applies to the whole question, not just to any particular school of thought about answering it. This was known since approximately the time when physicists first had access to Planck's constant, Newton's constant, and a spare envelope to write on. But, as you say, this is far from all that people who get called string theorists work on. A great pile of mathematical tools have been developed, to the point where deliberate ignorance of all of them would be a very strange position. Not for all fields of theory, obviously, but for quite a few.