It is a criterion but not a way to generate theory. In fact the key turning points mentioned are those theory (qm and r) both tried to explain something theory

It is a criterion but not a way to generate theory. In fact the key turning points mentioned are those theory (qm and r) both tried to explain something theory failed itself (the crazy energy of ultraviolet like today zero field energy) or observation that cannot be explained (increase intensity does not give your more electron in photo-electric effect but frequency does, like dark energy and matter these days). Popper is more against social “science” like Marx or philosopher like Plato. Whilst it clean up the field a bit not sure it is that helpful.