When you're debating opinion, the simple act of entertaining someone else's opinion validates it. There's no reason to engage someone who simply thinks you suck.

When you're debating fact, acknowledging someone else's facts grants them validity (note that if their arguments are accurate, they already have validity; the only question is whether you want to increase their platform).

If "random blogger" says "this book is about rape" when it isn't, there's no upside to even reading "random blogger." If "NY Review of Books" says "this book is about rape" when it isn't, there's every upside to engaging the NYRB.

If "random blogger" makes a cogent argument as to why your book is an apologia for rape, there's no upside in broadening "random blogger's" platform. If "NYRB" makes a cogent argument as to why your book is an apologia for rape, they'll ask you to respond before they publish.

This is one of the biggest holes in the internet people can fall through: you and I can be equals. Same age, same city, same hobbies, same paycheck. But if I write a blog and you don't, you get to tear me to shreds and the worst thing I can do is engage you. Total anonymity, transitory anonymity, and conditional anonymity all have more freedom than identity. Identity has more authority, however. The trick, then, is to resist using your identity to lend credence to conditional anonymity.