Manufacturers and retailers put enormous effort into marketing and advertising, often making grandiose claims about their product or service. But as long as these claims aren’t overtly deceptive (or flat-out false) they’re typically legal. A deceptive trade practice is activity by an individual or business that is meant to mislead or lure the public into purchasing a product or service. (findlawdotcom/state/consumer-laws/details-on-state-deceptive-trade-practices.html)
In my opinion Blizzard used deceptive marketing to push D4 and delivered an unfinished product to consumers, they should be held responsible for this malfeasance.