(Not trying to be judgy. People just seem to forget about the gender neutral use of "they".)
I found it actually fairly annoying at first, but quickly got over it because it is related to the plot. Same for Sanderson, I've read all his books and am not even sure now which one you're talking about!
Sometimes we need a nudge to notice the unconscious bias around us, and it's often uncomfortable.
The whole genderless thing was completely irrelevant to the plot—the diones could have been male or female and little else would have changed. It's not that it made me uncomfortable, but it was an unnecessary distraction.
Anyway, the book was a 2/5 because it threw almost everything from book 1 away, had way too many characters and places, ended on a serious cliffhanger, and the fictional science was extremely far-fetched. Meanwhile, book 1 was fantastic (a full 1/1 in my opinion) was focused on a small cast of characters on a small set, had great character development, and resolved nicely.
Not really: https://www.merriam-webster.com/words-at-play/singular-nonbi...
How is this offensive to anyone??