The unreliable narrator lends a particular type of voice to a story. After breaking down unreliable narrators by gender, Elizabeth Weinberg concludes that there are differences between male and female unreliable narrators—primarily, that male narrators lack empathy.
I’m a firm believer that although most fiction isn’t autobiographical in the sense that the events of a story actually happened to the writer, writers tend to write about what they find psychologically compelling, and they tend to write about what they, on some level, know. Which means a proliferation of characters, particularly male characters, who lack empathy probably points to a proliferation of people, particularly men, who lack empathy.