Sure blame the experimentalists. If the theorists are so smart maybe they can use their immense brilliance to draw on their chalkboards with femtoscale precision. All joking aside, while you are correct that we don't really have the technological ability to advance on a better theory of Quantum Gravity. But theorists need a rich experimental backdrop for their work to be meaningful. Since this is lacking, theoretical physics has produced a glut of plausible models that all arrive at similar answers from very different first principles. This leads to the sense that none of them are decisively right or wrong and the pursuit of yet more models is a meaningless project. Yes the root problem is with the experimentalists, but the theorists suffer the consequences.
I wouldn't even go so far as to say it's either the theorists or experimentalists fault. The problem might just be that it becomes physically impractical to the point of practical impossibility to observe the nature of things beyond a certain scale to us. And that's just, you know, the nature of things.
