It's been discussed on several posts with different forms but there is not a one specifically saying:
1) each object (page, asset, comment) should have it's owner
2) the ownership can be
  • given to anyone by the owner
  • taken by users with appropriate permission (administrators=globally + page rules)
3) add new page rule
  • Assume page ownership
  • Assume asset ownership
  • Assume comment ownership
4) add new permissions:
  • Edit+Delete own pages only
  • Edit+Delete own assets only
  • Edit+Delete own comments only
This would push whole permission settings to a new level.