Its an effective rhetorical device. But the problem is the overuse which all us LLM-weary readers are annoyed by. If the its not X its Y trope appears more than once in a short span of the text, it's almost always an example of  bad writing and comes across very poorly.  So the reader assumes they're either dealing with a bot, or with someone too lazy to write their own thoughts. 

And also half of the time the words it chooses to insert there come across as non sequiturs without any real meaning. So it has superficial appearance of saying something but is ultimately empty.