I don't think just stating what it does will mean much to anyone.
If you reduce this to "removes non-matching attributes from a collection of cubes", how many people, seeing that, are going to have any clue why would you ever want such a thing?
In the past, we have added extended usage notes on new features for this purpose.  
I don't think that is warranted here, but I do think that without some hint as to why you might care, there is not much point having a whatsnew entry at all.