Thanks for pointing that out; maybe one important part that I left implicit is the feedback coming from domain experts (such as the staff of a major publishing house).
The dichotomy is not that simple.
For example, in many areas of math it is of tremendous benefit to be able to internally visualize (with your "mind's eye") complicated structures and how they 'move' in relation to each other. Whether it's a skill or a ability, I've noticed some striking similarities to the internal visualizing skill needed in drawing:
To believably characterize a human figure in movement on a still paper that does not have ability to represent movement, it's helpful to see underneath the skin, to visualize all the muscles and bones and what they do when the figure moves. To draw a face, how the different muscles and bones and tissues are structured and form a face; to draw it with a certain emotion, how those certain muscles contract when you smile, and so on.
Or that was the gist of the my high school art class (I wasn't that good at it, but I have noticed the relationship.) And you do have a point it's useful to take a class (or find a book that adequately describes the contents of class). But the point of this example is that there's surprising amount of granularity [1] in the domain of mental skills, which is finer than "purely intellectual" vs "physical / emotional".
[1] in lieu of a better word
Now most people who do that will end up terrible writers. But when someone like Eliezer does it, the results are spectacular.
You could have found a more convincing example.
The objective metrics of quality of literature are hard to come by, but HPMOR does suffer from quite many, many stereotypical sins of fanfic / bad genre writing and makes a tiresome read. (One that I found especially grating and made me finally drop the story altogether could be described as "my main character is not OP because I set up these plainly arbitrary obstacles as a 'balance' ". Please, no. There's more to writing enjoyable, interesting characters in meaningful stories than such naive "balancing". The preferable end result is a piece of fiction that has something more going in them than surface-level entertainment plot which is amenable to measured in terms such as "is my character OP".)
However, I did not register an account just to lambaste Eliezer's fiction. Here's a couple of points that hopefully tie this comment to the main thread of discussion (so that this contribution provides some signal instead of pure noise):
Taking a year-long course in lit or at least some input from the tradition of literature might have improved Eliezer's writing. A class isn't the only way to attain that input, but it certainly helps in finding out if you have missed something vital in your self-study. (After finding out those pieces of information you are free to judge and dismiss them, too, if you want, but you are now dismissing that information with the knowledge that it exists, which is prone to make your act of dismissal more intelligent and productive.)
I don't have exhaustive collection of biographies at hand, but I believe the general trend in "successful writing" is that the significant portion (probably majority) of successful writers (including, but not limited to, authors included in the Western canon as creators of "good literature"), read a lot, wrote a lot, and had a lot of corrective input to improve their writing during their writing careers. Actually, I wouldn't be surprised if prior to starting a writing career, they already had lots of corrective input to improve their general storytelling skills before they even started considering writing. The input came in the form of teachers, friends who reviewed their manuscripts in process (or commented on their stories), how popular their first published drabbles were, and (often most importantly) the input given by the publishing house editors whose job is to improve writing of authors who submit their fiction for publishing.
I believe that a network independent bloggers [0] who are not tied to a single forum centered on discussing E.Y.'s writing would be an improvement: Intellectually more versatile and thus healthy; can avoid echo-chamber effects. I wasn't active on LW at the time pf peak activity, but I've understood that one of the objectives of LW was that "rationality" (whatever is meant by the word) would spread outside a single corner of the internet.
However, the problem is finding all those interesting, rationality-adjacent bloggers: if there's no any central place where you can find those people and their contributions, it's not a network: it's just random unfindable people.
[0] Or FB / etc writers, but I have preference for public, open web.