We can't protect everybody from everything and we shouldn't be trying. We already do a pretty good job and that's as much as we should attempt.

We shouldn't be trying to protect everybody from everything. We should be trying to protect people from the negative consequences of our own activities (i.e. setting up an "anybody can edit" infrastructure that any person can edit with substantial insulation from the consequences, and leaving that infrastructure in place once it became one of the largest sites on the internet and among the top results for many Google searches.

We are writing about people without their consent and broadcasting what we write to an extremely wide audience. We have the legal and, generally speaking, the moral right to do that. But we (and here I mean "we" as individual contributors) also have the legal and moral right to ensure that we avoid damaging misinformation. As Greg said, there's plenty that we could do but don't do in that area.

Moreover, this isn't a mosquito: OTRS gets e-mails every day from victims of defamation. If the defamation was committed by a registered account, they have no legal recourse - the WMF is immune as a common carrier, and the subject has no way of finding out who actually committed the defamation (and even if they could, the offender's as likely as not to be a fifteen year old with no assets). Wikipedia enables the hurting of a lot of innocent people, and we should take reasonable measures to reduce that enabling.

Steve