Accuracy is a bad measure for the reliability. Precision and Recall (Sensitivity) would be a better measure.
The article mentions that „The blood test’s sensitivity for colorectal cancer is similar to stool-based tests and lower than that of colonoscopy, which Grady still considers the most accurate screening test for colorectal cancer.“
Thus not even providing insight into the actual benefit over colonoscopy or stool-based tests.
I didn’t thought of it this way. I agree with you, that this would be the greatest benefit.