Thanks for your answer, I understand but I agree with the user of issue19172.
With the actual permission system is not possible to ensure private access to data.
For most companies, most dashboards should be open to everyone which is what optimize for.
If you really need that level of permissions, then I would look at the multi-tenant solution and use separate orgs. Different orgs cannot see each other dashboards or data.
I don’t know if it is a complicated modification but adding the capabilites to change/modify the default permissions will be ok for old users and new request.
Moving to multi org architecture will be a too complicated solution for me