It is because the old system was just mute, kick, and ban. However, some members are particularly interesting to interact with, and therefore the “prison” came out for those who are not suitable to chat in other channels to only chat in the prison. Quarantine, on the other hand, forbids the ability for the user to see any channel except let’s chat and server news. This is a way to keep them updated on what is going on yet unable to say anything in the server, which is a better version of kicking.