Can anyone tell me what's wrong with this procedure?
There's nothing wrong with using AI writers, Surfer or other tools to aid content creation.
However, even though the content reads as original, more often than not the semantic information isn't. In your examples, It's basically the same content, just said in another way.
This is what google looks for when determining the quality of a piece of content. Identical semantic information automatically indicates the writer has used data already ranking highly online to compile their article, and regardless of what tools were used, is deemed surplus to requirements for that specific search intent.
Using tools or writing techniques to be as good as what is already ranking, just doesn't cut it any-more in the originality stakes. Let's take one of your phrases as an example, and rather than rewriting it, we'll semantically add to it...
"Your brain cannot tell the difference between real and imagined memories. As a result, when you vividly imagine something, your brain chemistry changes as if you had experienced it."
"Your brain, which consists of the cerebrum, the brainstem and the cerebellum, cannot tell the difference between real (physical construct of reality) and imagined (created by a widespread neural network) memories.
As a result, when you you vividly imagine something, which is the ability to form pictures or ideas in your mind, your brain chemistry (the function of neurotransmitters) changes as if you had experienced it."
This is a very quick example of adding entity depth, without rewriting the content, vastly improving the authority of the statement. Basically, when comparing the two pieces, which one would be considered to be written by someone who understands the subject and wants to provide the reader with as much context as possible.
As far as I know, no tool available can add value to content like this.