I agree with Tommy. This isn't about who deserves the credit for running a marathon. I'm not even remotely pissed that people think I'm not as hardcore as their niece who qualified for Boston, just because I don't run marathons. I don't run to impress people.
The problem is that the marathon plodders, by and large, are not doing something good for their health. It would be fine if they were all like The Penguin, because then they would be running consistently and getting healthy. But most plodders are one-and-done marathoners. They push themselves through something that they're not prepared for, and they end up hating running. I have huge respect for the mental determination it would take to do something so painful and unenjoyable.
I always encourage beginning runners to stick with the 5k for a while, and to try to improve their times before moving up in distance. Unfortunately, all of their role models in the recreational running world only run 5ks when they're not actually training for a marathon. They don't see it as a serious race in and of itself.
Some of the comments from plodders about how long they've trained are revealing. Six months is not that much time when you consider that most successful marathoners have been running competitively, year-round, for a decade before they start marathoning. Trying to run a marathon in one's first year of running is like trying to write a dissertation before getting a BA. I suppose one could manage to painfully churn out 300 pages, and they'd certainly learn something from the process, but if one's goal is to learn, there's a better way to start. On the other hand, if one's goal is to do something difficult, deriving no other benefit, then I suppose you can do the job by writing dissertations in high school or running marathons on just 500 lifetime miles. Whatever gets you off...