The thing is, the people that weren't the ones posting the content. It appeared their computer was affected by some type of malicious file to be part of a bigger network. (botnet?)
I could see from the thousands of different IPs in different countries around the globe, that it could be affected personal computers.
Very few of them were computers from hosting companies, the rest were normal people computers.
I'm sure these machines were doing the job, someone else would have tests the result.
When we did the shadow banning it didn't made a dent in their effort.
The way they changed email, changed username, tried to be unique was completely prepared specifically for our platform (I would guess so)
Whenever we counter their attack, they would be silent for a while and then attack again. They would adjust.
Shadow ban is effective when the attacker themselves will not be aware it, in our case it was tricky to know who was the observer.