My first paragraph was a quote from the page itself that I was questioning. I was highlighting what the Rook gains from adding either Bishop or Knight move, and what both the Bishop and the Knight gain from adding the Rook move.
Could I also point out that '-boundedness' is not the right term here? Bounded is the past tense of the verb to bound, meaning to jump or leap or hop (in a general sense rather than the specific Chess ones), and as an adjective it means having a boundary so '-boundness' would be more correct - although so is the even briefer '-binding'. There are analogies with other verbs - you can ground an aeroplane and get a grounded aeroplane, but if you grind coffee you get ground coffee - not that I'm offering any.