There was nothing "to keep alive" when they sold PCI Express -bridgechips just to enable SLI-support, even though they weren't actually required
The argument isn't that there was a valid technical reason for that particular chip to be there, but that it was an understandable last ditch effort by Nvidia to keep its foot in the door after being elbowed out. Had that been allowed to continue you would have no doubt seen Nvidia attach more IP into future chips to more firmly entrench themselves. That's not an argument that it would have been better for consumers, but if they were wanting to maintain a presence on motherboards it makes a lot of sense. Whittling their actions down to sleazy short term business tactics for the sake of fleecing consumers for a few extra dollars doesn't give them very much credit in terms of longer term market strategy.