But the original set-up, where they were not* classified as a publisher, appears to be the ”Get out of jail card.”
* How was this possible? Read and weep.
This is under US law.
There's surely no reason [apart from being frightened of upsetting massive global corporations] why another jurisdiction couldn't pass a law defining the beneficial owner and controller of any website address as being deemed to be the publisher of anything shown there (whether generated by others or not). An exception, in the case of lower level transgressions [ie not fraud, incitement to violence, etc etc], might be allowed where the contributed item contained explicitly, within its own text, the name, address, and other contact details of the author of the contribution, and the website owner had reasonable confirmation that those contact details were correct - then the contributor could easily be held responsible directly.
A newspaper publisher can he held accountable for something actionable on their letters page, for instance, even though someone else wrote the letter. If people want to say things online without being vetted in any way, they can buy their own web domain and publish stuff directly, in the same way that someone who doesn't get their letters published in a newspaper can produce their own leaflet and give it out.