If the ideas are not complex enough to warrant a long explanation, it is a failure of the writer to be unable to produce the same information more succinctly.

Its not about short-form content, its about the unneeded over verbosity being a sign of a failure of communication.

Following Grice's maxims of communication, you can infer that they are either poor communicators or worse trying to hide something.

“I didn't have time to write a short letter, so I wrote a long one instead.” - Mark Twain

The complaint is about the lack of writing skill:

  Nearly every blog post I have read in this ecosystem, even the rare one that contains some good ideas, is painfully long and extremely tedious.

Rationalism is for people who enjoy jerking off to their supposed superior intellect while reading bad Harry Potter fan fictions.

The author didn't say that they wanted a short video. You're constructing a strawman to gleefully knock down. How very "rational".