Keeping discussions of deleted users

[Pierlou]

As it stands, when a user is deleted, we also delete all comments they made on any discussion. I am wondering if we want to keep this behaviour, as I have just come across a case where this could be problematic:
let's say a user is a member of an organization and answers questions on behalf of it. When the person leaves the organization (in reality, like changes job or anything), it could be that either the person or the other members of the organization delete the person's account.

Currently, if this happens (spoiler: it's just happened), the conversations have blanks, or are entirely deleted if the user started them, and potentially relevant/important information is removed.

If we want to change this, it's here.