Do you allow members to delete forum posts?

Do you allow members to delete forum posts?

I have been running forums now for around 10 years and one thing I learned back in my early days was to not allow members to hard delete posts on your forum. I learned this the hard way after I had a member come onto my forum whilst I was away from the forum and post up vulgar messages and images but delete them before I could see them meaning I had no grounds to ban them without proof of what they had done. I have also come across members bullying other members on forums I have run and then again hard deleting the evidence so there was no proof. This pushed me to stop allowing members to hard delete their posts and instead only be able to soft delete them so that they are still visible to staff.

Do you allow your members to delete their own posts? If so do you allow them to hard delete the post meaning it is gone forever or do you only allow the post to be soft deleted?