Deck building would help some of the lower ranked books. Chaos Marines are great at summoning things, throwing cultists in a grinder, and camping. But not moving or shooting. If they could score points for tar pitting more points than the unit is worth, they might win some games. Something like "Remain in assault with more points than your squad is worth and score 1 point. Make it 2x as much and score d3 points" and "Summon some crap, score a point". But all of the stuff in the book favors fast, shooty armies, not games of attrition, which is all Chaos really has. And it would require me to buy more crap from GW.