Earlier quoted context omitted.
For the same reason when some fellow citizen acts against you, you may need to sue them yourself - Google provides a platform with some set of rules, but they can't proactively ensure nobody is doing something malicious to other parties (especially if the malicious act is allowed by the rules), nor they can codify and enforce "don't be an asshole" rule.
Your analogy doesn't really hold up. This isn't another person coming after you directly, it's the other person manipulating a third party to cause the third party to come after you, and the third party saying "not my problem that I'm easy to manipulate like that". For a criminal-justice-system analogy, it's similar in concept (though not in extremity) to SWATting. And I don't think we want governments to wash their…
https://en.wikipedia.org/wiki/Swatting
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