Actually Krugman did give an explanation: "It’s not just about the money, although that’s important [...] What matters is whether it has too much power, and is

Actually Krugman did give an explanation: "It’s not just about the money, although that’s important [...] What matters is whether it has too much power, and is abusing that power. Well, it does, and it is." And why that abuse of power is a bad thing: "It’s definitely possible, with some extra effort, to buy a book you’ve heard about even if Amazon doesn’t carry it — but if Amazon doesn’t carry that book, you’re much less likely to hear about it in the first place."