Because it's insanely difficult to create a work of the size that he did without making a few mistakes here and there. The fact that you don't know this is evidence of the fact that you've never tried.
> Any book of Why We Sleep’s length is bound to contain some factual errors. Therefore, to avoid potential concerns about cherry-picking the few inaccuracies scattered throughout, in this essay, I’m going to highlight the five most egregious scientific and factual errors Walker makes in Chapter 1 of the book. This chapter contains 10 pages and constitutes less than 4% of the book by the total word count.
I know, I read it, and two possibilities suggest themselves:
1. There are many many more errors in the book, and the Guzey, not being very well organized, chose to highlight the fact that the author was wrong about cancer and lifespan (who isn't), and a couple facts not really related to the main point.
2. Despite claims to the contrary, Guzey is cherry-picking the few inaccuracies.
