Just a few "core banned subjects?" Is that so? Let's test your theory on a non-banned topic: air pollution.
Suppose a Chinese netzen went on WeChat and said something like "air pollution is out of hand, and the local government isn't doing enough to stop the polluters. Let's all meet up next Saturday at noon in central park, and then we'll peacefully march to city hall and protest its lack of actions."
Test 1: would the CCP Internet gstapo notice?
Test 2: if yes, would CCP allow the gathering to peacefully protest?
Test 3: what would happen to the original poster? Nothing? Aggressively told to knock it off, but nothing bad happens to him or her? Thrown in jail a few days to cool his/her jets? Exiled to a gulag where s/he is horribly tortured with hours and hours of Rap music?