It's also amazing what you can say if you don't care who's attributed. Anonymity or pseudonymity can be of great value here.
For someone of Livingston's stature, writing under a pseudonym may not seem as attractive an option. When sharing anything really valuable, via a pseudonym, there's no opportunity to leverage existing audiences, or build reputational equity for your 'true name'. And for the already-prominent, if a pseudonym is later pierced the blowback can be larger. So why not spend your time and words elsewhere, either on safe topics, or only sharing 'dangerous' thoughts privately?
Thus Livingston mentions, in her footnotes, increased sharing in controlled environments with trusted associates – as on Facebook. But most people may find pseudonymity the best strategy for collecting the benefits of freer, more honest speech.
I even suspect that a "right to create uncorrelated secondary identities" may be a crucial 21st-century freedom, worthy of encoding in law and custom.