What is the benefit to requiring proof of jurisdiction, and do you really see that benefit being worth making most Internet forums — including this one — almost impossible to run legally?
It seems to me the end effect of holding hosts' liable for users' speech would be that only the rich are allowed to communicate anything on the Internet.
Those who are causing hurt remotely from a country outside any jurisdiction where the victim can realistically get help are already immune to justice.
This discussion is, in large part, about whether services that knowingly or unknowingly help such people to cause harm but are within a jurisdiction where the victim can realistically get help should be immune as well.
I wouldn't necessarily go as far as wang_li suggested in their first comment on this thread myself, but the general sentiment isn't unreasonable.
It seems to me the end effect of holding hosts' liable for users' speech would be that only the rich are allowed to communicate anything on the Internet.