Address Book in Mac OS X Leopard & Snow Leopard was probably peak in the "Design is how it works" part of that quote.

Notice how the + symbol is in the bottom bar, corresponding to each column. There is no confusion where a new "item" (whatever “item” may be), will appear.

Today, if you look at Notes, the + is above the editor/note view -- and not over the list of notes column (where it actually appears). I mean, I could see that work but it's an odd setup.

This design here is far more clear.