I don't know if this is the main reason, but I read an article saying that Chinese companies were starting to export this tech to other countries. So that would be one way to "advertise" its effectiveness.

Also, the more China gets other countries to enable the same kind of censorship and surveillance it does, too, the more it won't stand-out as a sore thumb and the less it will be called out by "principled" leaders in the future.