You're mischaracterizing their argument. They're saying that people who are poor at resisting impulsive behavior tend to be less successful because they're more likely to get caught up in problems associated with poor impulse control. Credit card and gambling debt, drug addiction, getting in fights, etc.
It's about people who fail since they consistently choose to spend time getting wasted or playing WoW rather than studying, practicing, or other things that pay off in the long-term. This isn't about conformity, because it specifically includes people who have trouble meeting their own goals.
It's interesting. But (regarding parenting):
"Have they established rituals that force you to delay on a daily basis? Do they encourage you to wait? And do they make waiting worthwhile?"
In life, delaying gratification often pays off - but only to the extent that the provider of said gratification is competent and trustworthy. There are also times when it is genuinely better to take the money and run. Your bank, for example, has little interest in giving you a fair deal, but instead offers financial instruments with superficially attractive terms while burying numerous modifying clauses in the fine print. An employment contract from a major corporation can be similarly unfair. My first cubicle job came with an employment contract that asserted ownership of any intellectual property I produced during my term of employment.
One example that springs to mind is Shuji Nakamura, who has been a major innovator in the field of LED diodes (specifically, he's the engineer who made high-intensity blue light available on the cheap, so if you've got a Blu-ray player you should thank him). For this, his grateful employers bestowed upon a bonus of...$180. He sued and eventually ended up getting $7 million.
Many actions don't have a clear party (parent, teacher, boss, etc.) waiting to reward or punish, though, and the research is specifically about self control. While some people will take advantage of others' responsible behavior, self-sabotaging behavior probably has a greater overall impact on most peoples' lives.
Good example, by the way. I hadn't picked up on it reading the article, but the study really does assume an immediate observer is going to be rewarding the child, rather than more abstract forces such as the job market. The latter is hard to duplicate in a self-contained experiment, of course.
It's about people who fail since they consistently choose to spend time getting wasted or playing WoW rather than studying, practicing, or other things that pay off in the long-term. This isn't about conformity, because it specifically includes people who have trouble meeting their own goals.