is Pooh making sure he's surrounded by loyalists?
edit-if the PRC wasn't an authoritarian nightmare, perhaps our Chinese posters could discuss, ya know, internal Chinese issues
The thing is, the people who were recently purged
were his loyalists. When he came to power in 2012, he immediately went for the jugular and started reshuffling the military. At the time, the PLA was so corrupt that promotions were openly for sale. The top brass were locked up, and many other generals were allowed to retire quietly if they pay back their cash.
A decade later, it appeared that Xi had successfully created a new cadre that wasn't enmeshed in the previous grift machine.
Having to replace multiple top brass makes a mockery of Xi's efforts, and indicates that he doesn't trust his supposed loyalists a decade into his rule. It also makes a mockery of the widespread idea that "Pooh is a b*tch, but at least he cracked the whip at all the grifters".
By the way, the Defence Minister isn't actually in charge of the military. That job belongs to the CCP's Central Military Commission, which is chaired by Xi himself. So, officially, the PLA isn't the government's military, but is the CCP's armed group. The Defence Minister acts more like a liaison with other countries' militaries.