I’m really sorry: this feature does exist in 7.6, in the “new filter” referred to by @anon291708:
I had even used it to save my list of consultant-checked books, but I’d forgotten that I’d done that. Being able to name and save sets of books is excellent!
My only comment would be that the box and buttons are very small, and tucked away in the top left-hand corner – which is consistent with the save-named-project-list feature that three or four relevant dialog boxes use – maybe they would be more visible in the lower left, under the other selection buttons?