>does that necessitate sharing a single instance across thousands of unmonitored models running without safe-guards?

The only difference with having a single instance is that it can be abused as a message board. It doesn't prevent it from getting hacked to access the open internet. Blaming "sharing a single instance across thousands of unmonitored models" feels like blaming the drug epidemic on e2e chat apps rather than other factors like poor border security or the easy availability of fentanyl.