Spoiler alert: It’s a quill pen and ink.
Don’t get it?
The quill pen and ink imposed a cadence on users that translated into how they write: Word, word, word, word, word, (maybe word), (maybe word) [dip the pen; you’ve run out of ink.]
Short sentences communicate more easily.
It reminds me of my high school Latin teacher who expounded on the benefits of Anglo-Saxon over the latinized Norman speech: Simple words in simple straight forward sentences.
Or, as the Inc. subhed stated,
Keep your words simple and your sentences short.
On a completely unrelated note, my new suspense novel, The Mark of the Spider, contains lots of simple words and short sentences.
Get your copy (in print or ebook) from Amazon and see.