The population registration scheme that Chen Xi devised for the Ming Dynasty was far too sophisticated for this era. At least Ju Shou and Xuu You, despite being considered first-class intellectuals in this day and age, never even considered that all the intelligence under their control could be false information deliberately fed to them by Mount Tai.
In short, because Li Youu and Lub Su had too many things on their plate and the initial rollout of the new population registration was quite complicated, the scheme really only took off in Mount Tai Commandery. As for Qingzhou, it was still in a gradual phase of implementation.
Indeed, even this incomplete version of the population registry was enough to utterly ruin the intelligence network that Xuu You had painstakingly built. After all, Xuu You was investigating Li Youu, who lacked any prior records, so the only information Xuu You could probe into were the events surrounding Li Youu's arrival.