Even if optimizing your appearance adds little marginal advantage in any given situation, it adds up quickly, and I suspect that advantage can actually be fairly large in situations where there's not much to go on except a first impression.
I in general agree with this assessment. It does add up. But there might be an area where it doesn't.
To give a concrete example: During school I avoided fashion, pop culture and socializing. I felt that it gained me nothing and take time away from my much more interesting subjects like math and (later) computer. Arrogantly I thought myself above this. Intentionally misunderstood jokes. Committed to be different. This made me an outsider during school (luckily without becoming subject to bullying). But it did allow me lots of time to study.
Only much later when my interests expanded to include evobiosociopsychology did I really grasp the effect. I believe that I have been a quick learner since. The only penalty that appears to be difficult to compensate is relations. I have only a small circle of acquaintances and I'm not sure I can (or want to) build it up. But I'm also not completely convinced that the business landscape requires this.
To end the example: Is it worthwile to focus ones skills on one area - an intellectual area that my promise to pay back with compound interest later - and to pick up other areas later (though possibly completely excluding some areas)? Or should one rather advance all areas at once (albeith possibly with different weight)? Or does it depend?
For me it was a most successful strategy so far - though it could have been just luck and chance.
In Magic: the Gathering and other popular card games, advanced players have developed the notion of a "win-more" card. A "win-more" card is one that works very well, but only if you're already winning. In other words, it never helps turn a loss into a win, but it is very good at turning a win into a blowout. This type of card seems strong at first, but since these games usually do not use margin of victory scoring in tournaments, they end up being a trap-- instead of using cards that convert wins into blowouts, you want to use cards that convert losses into wins.
This concept is useful and important and you should never tell a new player about it, because it tends to make them worse at the game. Without a more experienced player's understanding of core concepts, it's easy to make mistakes and label cards that are actually good as being win-more.
This is an especially dangerous mistake to make because it's relatively uncommon for an outright bad card to seem like a win-more card; win-more cards are almost always cards that look really good at first. That means that if you end up being too wary of win-more cards, you're going to end up misclassifying good cards as bad, and that's an extremely dangerous mistake to make. Misclassifying bad cards as good is relatively easy to deal with, because you'll use them and see that they aren't good; misclassifying good cards as bad is much more dangerous, because you won't play them and therefore won't get the evidence you need to update your position.
I call this the "win-more problem." Concepts that suffer from the win-more problem are those that-- while certainly useful to an advanced user-- are misleading or net harmful to a less skillful person. Further, they are wrong or harmful in ways that are difficult to detect, because they screen off feedback loops that would otherwise allow someone to realize the mistake.