TL;DR

To protect against the most commons threats that arise from online data harvesting from government, companies, and fellow humans.

Common threats include, phishing scams, credit card fraud, identity theft, targeted marketing, stalking, and surveillance.

https://modusb.com/nym

https://github.com/BlockchainCommons/Pseudonymity-Guide/blob/master/01_1_why_privacy.md

https://www.citadel21.com/true-names-not-required