Whereas, it is a huge time saver (and pretty standard for good reason) to view the work that needs to be done, rather than incomplete tasks interspersed with completed tasks.
And, the default is Asana is to show all work.
It should make sense to make the default view for all boards “Incomplete tasks”, rather than have every user change every board to this view when they want to focus.
Barring that capability, it would make sense to allow users to set a global, personal view for all boards they participate in to the focused view of work still to be done, unless otherwise reconfigured as needed on a per, board basis.