Like I said, you would use both browser fingerprinting and IP address to identify people. So hopping IP addresses wouldn't be enough by itself. If you're curious about how browser fingerprinting works, there's this neat website: https://coveryourtracks.eff.org/ where you can test your browser. It's a fairly accurate way to track people across the internet. A dedicated person could bypass these systems, but a dedicated person is also more likely to be aware of shadowbanning.
Shadowbanning is most likely to affect people who don't understand a lot about how the technology and systems of a social media site work.
After a certain point, you just have to accept that there will be some trolls that bypass the system but it's not worth finding 100% of them because you'll catch a lot of regular people in the process. There's that famous statement with the criminal justice system "better 10 criminals go free than 1 innocent man go to jail"