Would it be possible to let users delete their account and when users delete their accounts you could override all PII with a "default" value? It's meeting users midway where their comments are still visible and threads are not gutted but they are not associated with their PII anymore?
When users delete their account, instead of deleting the content/comments they submitted, you could replace the deleted user's username with the value [deleted], replace the IP address, email address and any other PII collected about the user with the value [deleted]. That way the threads remain intact and the content is not associated with the users anymore.
Ok, I think I understand. We wouldn't replace all such usernames with [deleted], for reasons I explain here: https://news.ycombinator.com/item?id=23624019. But we randomize them, and if that's not enough, there are sometimes other things we can do.