Well, ok, but it’s also that apps like Grammarly and Hemingway have a low opinion of the average reader’s vocabulary and the length of time that reader can hold the beginning of a sentence in their memory. Because of that, they want simple words and simple sentences.
The apps are probably correct. If I use uncommon words or join too many thoughts in a sentence, I may confuse some people.
“Frankly, my dear, I don’t give a damn” sums up my reaction.