> Do you really think the government needs to get involved when no demonstrable consumer harm is being done?

Generally no, but I don't think a monopoly is a prerequisite for biased incentives to cause consumer harm, particularly for platform companies. Consumers don't have to choose between a bunch of non-monopoly platforms that aren't acting in their best interest when they can collectively decide, via their government, to force the platforms to do as they want.

This is speaking generally - I don't actually have any problem with the specific case of Amazon promoting their AmazonBasics brands.