I'm 100% certain that China has many more spies in US than vice versa, and that America haven't ever penetrated into serious high up Chinese elites, whether they were corrupt, or not because of Chinese secret police.
Basically. But I think "long-term thinking" implies grooming was suppose to eventually develop into useful assets if corruption culture persisted. Even if unlikely. Hence one motive, likely small but still significant - few dozen execution of CIA assets among million+ disciplined by CCDI. Along with "notable professionalizing of the Ministry of State Security" implying domestic counter-intelligence was previously lackluster, likely at lower levels. At least my experience in the 90s. Dinners with gossipy staff from JingXi. MSS officers chatty at weddings. One would hope opsec has improved since.
I cannot imagine that anybody seriously researching China never knew of that.
And I greatly doubt that just any benefit could've been extracted by US spies from getting hand on near 99% Chinese officials who don't know anything, and don't decide anything.
China's political elite is just few hundred people, and they were always surveilled by the state ceaselessly.