This was something that existed in GoodData and was very useful. We had a bunch of users that could create reports and dashboards in GoodData. The ability to restrict access to reports and dashboards was a big plus since you don't always need to see other agent's reports and may not want them to see yours.
In Explore, every query is visible to every user with Explore access. While the "My Queries" tab is useful for limiting the view, it is not the default view. As the list of queries grows this becomes more of an issue.
There should be a way to control what users are able to see. The dataset authorizations only limit the agent to "read only" for the queries within that dataset.
The owner being able to "lock" a query from being edited would also be useful.