There's a similar argument about athletics. Sure, the people who win gold medals and get MVP at the Super Bowl have amazing genetics, but they also worked crazy hard to get there. Your hard work isn't going to get you a gold medal, but if they didn't work for it, they wouldn't get it either.
The core message is good, though: if you don't have whole package, don't apply the polish. But if you think you have a shot, don't think you can skate by on what you already have.
This is wildly incorrect. Assuming you have a perfect score on every other part of the rubric, the maximum improvement you can get through the essay is 11% of your non-essay score. Without that assumption, the maximum improvement is positive infinity percent.
Edit: The closest thing that came to mind is the idiom "penny-wise and pound-foolish".
Offer a group of people the opportunity to design a nuclear powered aircraft carrier, and no one says boo, but ask them which color is prettiest for a shed to park their bikes in, and suddenly everybody puts in their two cents, ad-nauseum.
If you strongly desire a fellowship, I recommend researching which professors' students have gotten them in the past. Then, make sure you are on good terms with your PI, that the PI thinks you are a hard worker (whether or not you actually are), and write milquetoast essays that hit all the science buzzwords and PC stuff ("I'm interested in mentoring minorities"[0] - whether or not you actually do any of that).
[0] I actually did mentor minorities and didn't write about that in my essays, taking a more frank approach about what I thought was wrong with minority recruitment, and I lost out on a fellowship to a guy who now is a professor and has exactly zero nonwhite nonasians in his lab. Let's just say they don't really care about honesty and followthrough.
Incidentally, this student also had a research project where all of the data presented in the primary paper were artefacts of the preparation method (It didn't affect the overall conclusion). I confronted the student about this and even went through the process of repeating the experiment with a better prep, resulting in data that actually made sense. Some of the figures were completely invalid, and one of the subsidiary conclusions was wrong. I suggested that he issue a correction and at least stop talking about the subsidiary conclusion, but he continued to present it at several conferences afterwards, and as far as I can tell, the data have not been corrected in the literature. But he did get that fellowship. And now, is getting NIH grants. Your tax dollars at work.
From "Competition is for losers" (http://www.wsj.com/articles/peter-thiel-competition-is-for-l...):
"Always prioritize the substance of what you're doing. Don't get caught up in the status, the prestige games. They're endlessly dazzling, and they're always endlessly disappointing.” -Peter Thiel
...all of which are competitive awards.
Easy to say if you're a billionaire.
Which is a better direction? Investing your energy in solving a problem where no good solution exists today? Or competing for a corner office?
And an easier position for most folks to get into, if they aren't already.
This differs from the OP, where it is the ability to control an issue that is to blame - in Parkinson's law control is equal yet understanding is not.
Though of course the relation is strong.
This is taking something that really does matter, but it's too late to change most of it, and putting too much effort into the remainder.