Sorry but IMO the author has failed to prove his case. The text is not easy to read, and it's hard to follow the author's thought.
So long sentences and long paragraphs definitely don't help. It's either that or I should get tested for ADHD.
Short sentences are not about simplicity, they are about accessibility. While it was not hard for me to read his text. It did not flow, and was not easy to follow. Long sentences distract the reader with their additional complexity. Instead of being able to focus on the content, the reader must decipher the meaning. Then they can engage the idea.
Making it harder to understand content is a terrible way to communicate.