The point of the post is about overall profitability of adwords. An ad's CTR is important to drive as much traffic as possible and also to keep a high quality score, but you arent directly paying for people who do not click your links. However, you are paying for all the people that click your links and do not convert, so focusing on improving your conversion rate is one of the best ways to improve the profitability of an adwords campaign

Lower conversion rate ale signifies lower page quality which is another factor that AdWords use to calculate the ad position, and if and to whom to show the ad to. Which, in turn impacts click rates and so on, ad nauseam.