I'm not sure it's as obvious as the author assumes. In the shopping sector, there's a concept of 'minimum advertised price' that every online store respects, which is set by manufacturers under the same carrot-stick arrangement (i.e. it's the price the manufacturer believes would drive the value of the entire market sector down if it were common, shopping aggregators aren't allowed to show products below that price, and if they do the manufacturer cuts the high-density pre-digested feed of feature descriptions for the product).
It's clearly anti-market practice (in the sense that it adds information asymmetry between some part of the market and consumers in an attempt to keep prices higher), but it's being done by hundreds to thousands of manufacturers and it's real unclear on what criteria it'd be considered illegal.
Many information asymmetries (even artificial ones) are not illegal, and indeed, even the moral argument for changing the law may not be as cut-and-dry as one assumes at first glance (for example, if sale below M.A.P. drops the bottom out of a market and kills an industry, the product can disappear from common production and the consumer doesn't benefit in the long run).