One sentence per line makes prose feel sanctimonious, even self-aggrandizing. I find this dude's writing un-readable for exactly this reason. All of his articles are like HTML versions of the Ducks Go Quack TED Talk [0]. I just roll my eyes.
The first thing that stood out to me was the robotic nature of his writing. It seems like he's going so far out of his way to remove "unnecessary" words from sentences, and remove "unnecessary" sentences from his paragraphs, and to stringently vary his sentence lengths, that he winds up writing unnatural language. If you write in a way people aren't accustomed to, your readers are going to have a harder time understanding you.
"Sometimes short. Sometimes long." "Cut three lines. Paste them up above."
This isn't how English is used.
I think the idea is that, if your sentence can stand up to the added scrutiny you'll give it while seeing it sitting all alone, then it is worth keeping. Otherwise it is a wasteful sentence.
Anyway, I do agree that the actual "one sentence per line" prose that is so pervasive on places like LinkedIn is awful.
Paragraphs — like punctuation, grammar, syncopation, etc. etc. — express semantic intent. They're not, like, type faces. They're one of the tools that ·authors· use to communicate meaning.