While I admit to only skimming that link, all the examples I read discussed a single company tying purchase of one of their products to one of their other products.

Apple does not sell DUNS numbers, as they are not Dun & Bradstreet.

It also mentioned the anticompetitive nature of tying a weak/new product to a stronger one. DUNS numbers are not new or esoteric (although I do think of them as being old-fashioned and enterprisey).

So, I struggle with the notion that this could be illegal, but I'd be fascinated to learn more about it.

Sure is developer hostile and counter-productive, though.