I read her blog post. I don't see anywhere in her post that gives one concrete example of a negative impact on consumers.

She gives the example of Amazon.com forcing diapers.com to sell diapers at a lower price as a reason for why we need to prevent acquisitions. But getting products for cheaper prices benefits consumers... The small business founders got rich and consumers got cheaper diapers. I'm not seeing any problem with that.

She claims Amazon is anti-competitive because they promote their own products on their own website. Websites aren't railroads. Consumers can choose any website by typing in the address in their web browser. Consumers can switch search engines and shopping websites. That was not the case with railroads or phone networks - because for reasons that should be very obvious you can't have a million different railroad lines and telephone wires. Unlike the web, they were physically mutually exclusive.

If a company provided superior service and prices to Amazon consumers can easily choose to use them.