Short sentences help search engines 'understand' the text, because they can easily parse each sentence to get direct meaning out of it. If your article says 'Fire caused titanics sinking.", and someone searches Google for "Why did titanic sink?", then Google can return that snippet of your article directly. They can also look for similarities in meaning between your sentences and all other sentences on the web to find contradictory information.

If you use long sentences with twists and turns and double negatives, it's rare that such a direct match can be made to a search query, and your article won't be returned.

Finally I understand why a lot of online content (particularly that of a more obviously derivative nature) has become so relentlessly uniformly elementary over the course of the past three/five years.

I read for fun and mental enhancement. If articles become simple just for SEO optimization, I'm quitting the internet.

Even Wikipedia is starting to reflect this.

Or Ernest Hemingway