I think you're right that the government does have 'limit the size of companies' as a motivation, but I don't think that's their main motivation. For one thing

I think you're right that the government does have 'limit the size of companies' as a motivation, but I don't think that's their main motivation. For one thing, how would you even right and enforce a law on maximum size/impact of a company? How would this even politically get through? There's already enough push-back against enforcing laws like "don't form cartels". The pushback on maximum size/impact of a company would be even more intense. In any case, as the article states, "Today, Amazon tells sellers that if it detects a lower price for their products on any other online store, they will be punished, which is to say, their ability to get their products onto a place on the Amazon website where customers click will go away.". In other words, e-commerce is not extremely competitive.