It’s well-established that the internet is a vector for bullshit. So how does such infectious stupidity spread? There are two ways: fast and slow. ‘Fast’ are hoaxes that are shared thousands of times on Facebook and Twitter until, long after the damage is already done, sites such as Snopes debunk them. ‘Slow’ is more pernicious and harder to debunk. Regarding the latter, it begins with an article citing some methodologically flawed ‘study’, and then the article gets indexed in Google, and over many years the rankings of the article will rise as it gets repeatedly cited, creating a feedback loop of higher rankings and more citations even though the original purported study is either BS or wildly misinterpreted, as are all the copycat articles citing the original article and study. It’s like ‘fake news’, but over a multi-year period, not just a few weeks.
The origin of the ‘big words make you look dumb’ myth dates back to a study published in 2005 on the website Science Daily, The Secret Of Impressive Writing? Keep It Plain And Simple
The methodology involved the researchers substituting simple words in essays with more complicated words pulled from a thesaurus.
And then in 2006 the story got picked up by Collision Daily, citing a now-defunct website “Bad Language” that had cited the original study:
Then Oppenheimer gave all the writing samples — the original, simple ones and the modified, flowery ones — to 71 students to evaluate. The result? As the grandiosity and complexity of the language increased, the judges’ estimation of the intelligence of the authors decreased. Oppenheimer wrote up his results in a paper with the gorgeously ironic title “Consequences of Erudite Vernacular Utilized Irrespective of Necessity: Problems with Using Long Words Needlessly.”
The commenters, however, weren’t buying it. Here is the most up-voted reply:
It is not surprising that improper or unnecessary use of complex language would give the impression of a less-intelligent or ignorant writer. After all, the study intentionally carelessly replaced words specifically to measure reactions, and college students should be learned enough to notice.
A better study would be one that also includes the proper use of specialized words in order to compare readers’ reactions. When properly used, complex language tells a better story, and I believe that most readers do prefer greater clarity – something that can not always be achieved with simpler language.
And here is anther article, from 2011, again citing that 2005 study: Why trying to sound smarter can make you seem dumb
Again in 2011: 11 Smart Tips for Brilliant Writing
From NY Mag in 2015 Using Big Words in Your Writing Is Not Impressing Anybody
And again in 2015, by Fast Company: The Secret To Sounding Smart? Using Simple Language
There are dozens more. For the same reason Gladwell books are popular, it’s an appealing narrative, which is why it spread like wildfire.
Besides the 2005 study, which is methodologically questionable, there is actually no corroborating empirical evidence to support the claim that simple writing is always better or that big words lower the perceived intelligence of the writer. Well-targeted words that have a specific meaning can add both variety to writing and succinctness, instead of having to use six words when one may suffice. Provided the words are correctly used (instead of haphazardly plucked from a thesaurus), my hypothesis is that the complexity of writing and the perceived intelligence of the writer by the reader, are not inversely correlated. Complex writing is harder to understand, but this is not an indictment of the writer’s intelligence.
A reader doesn’t walk away from Moldbug or Nick Land thinking, “This guy is comprehensible..what an idiot!” It’s more like, “This guy is comprehensible…I’m not smart enough to fully understand it, but I can’t help coming back for more.” 
As for more empirical evidence, Scott Aaraonson’s blog Shtetl Optimized, which covers topics diverse and esoteric as social theory and quantum computing , is immensely popular, with the typical article getting hundreds of comments, yet I would wager that scarcely one percent of the general population is smart enough to understand it. Same for Slate Star Codex, although not quite as complicated, is even more popular. Articles from the newly launched Jacobite Magazine, in which obscurantism is a feature, not a bug, get hundreds of shares. Their most recent article, Political Violence is a Game the Right Can’t Win, was shared a jaw-dropping six thousand times on Facebook. The works of David Foster Wallace and Thomas Pynchon, although difficult to understand, attract a large following.  That doesn’t mean simple writing can’t succeed, but as the aforementioned examples show, technical, verbose writing can also be hugely successful.
Yes, simplicity is necessary if you’re writing tutorials, but that doesn’t mean such simplicity is also optimal for creative or expository writing. The frame of mind of someone who is reading an Ikea manual is different than, say, when they are reading literary fiction. For the latter, there is an implicit understanding that the reader will have to make inferences rather than having everything explicitly delineated. There is more ‘work’ involved, but the reader expects it and even seeks the challenge. Most of the people who parrot ‘simpler is better’ fail understand this distinction.
 In the case of quantum mechanics, such complexity is almost unavoidable owning to the complexity of the subject matter itself, than any deliberate attempt by Aaronson at being obfuscatory, but it’s still pretty amazing how popular the site is given the difficulty of the subject matter.
 Obviously, ‘mainstream’ books and websites get more traffic, but there is also considerably more competition and also marketing behind the most popular of niches.
 I don’t find Moldbug and Land that hard to understand, but there seems to be a consensus that they are.