"Relatable" is in the eye of the beholder, but its very nature is to represent itself as universal. It's shorthand that masquerades as description.
The problem arises when "relatability" becomes the sole interpretive lens.
Can you "relate" to being enslaved, for example? Probably not, but that should make the prospect of reading Frederick Douglass all the more enticing. Many popular texts printed in the United States before the 20th century dwell on religious thought in a way that seems strange to us now. How can nonreligious people living in the 21st century "relate" to that mindset? The realization "I don't relate to that" could be followed by a subsequent self-examination: "What is it about my life, and my time, that has made it so that I don't really get it?"
Rebecca Onion writing in Slate