Are you limiting the question to dashboards? The title of the post does, so this may be a foolish question of mine.
But if you mean this generally, I am beginning to find them very useful in RDDs and REST calls.
I had been taught that they are kind of silly, just use the dashboard filters. But there is a bigger world out there…
I also have tinkered with the idea of making some big queries as reports with the intent that they would always be printed/submitted as CSV. That way it could run in the background without tying up the client. (As opposed to a dashboard.)