Earlier quoted context omitted.
Paywalled for me. Can you give us the gist of it?
TLDR: The Economist tries to argue that without death camps there is no genocide; which is false.
I don't agree with that viewpoint at all. Both forms are vehemently barbarous, and the world has enough problems with genocide denialism that engaging in technical arguments over the definition is only going to give more cover to denialists.