They cannot stop P2P but they can limit crypto institutions or individuals (centralized) that offer exchange services to customers. One of the reasons for this is that they have many unregistered individuals or crypto firms that act as middlemen between buyers and sellers. It looks like people are avoided registered exchanges because they can be used to trace or track their transactions. In an authoritarian country, anybody can be a target of the government. It could also be that the government is targeting to make money from the registration of these exchanges. A country that is facing sanctions will seek alternative ways to get income. They will not be able to stop P2P transactions between two people because even in China Bitcoin still happens.