You mean like what you have in the clubs that are supposed to be the discussion alternative for public forums?
Just because we have that option doesn't mean we use it. I was an admin in the last version of Rev's club for example as well, and we basically never used comment editing/deleting except on trolls
Public forums with no moderation would be like what the clubs are: terrible people with no respect for each other being protected by the terrible admins who only want to see people at each other's throats. (that is my characterization of the site's 'serious' discussion clubs)