Ya to be honest, I though this would have been re-introduced by now - there was a lot more control over what a user could and couldn't do in V5 on a per page/blog basis.
Different editors/authors for example shouldn't be able to log in and have control over other editors/authors blog posts, or even see them. Makes no sense unless its a main site-wide admin.
Standard editors/authors really should be only able to view, edit, delete, publish, assign tags etc to their own posts.
Same applies to the individual page content others talked of above.