While I cannot speak for the author, I can conjecture what the author may be communicating. We live in a world with increasing levels of surveillance. Financial transactions are recorded and centralized, phone usage meta-data is catalogued and hoovered up, travel is regulated and tracked, Internet usage is monitored, and the drag-net of information collection rages on. There are proponents of the surveillance State that say, "If you have nothing to hide, then you have nothing to worry about." This trope is of course nonsense and unconstitutional (US) among other things. However, if you truly have nothing at all to hide, then everything about you is known or can easily be made known, because you hide nothing. For such people who have exposed all, there is no mystery, no discovery, no unknowns. And therefore, there is nothing interesting remaining to be known. "I don't need to talk to that person because I already know everything about them." At this stage, uniqueness, mystery, individuality has been replaced with a comprehensive fact sheet. My 2 sats on this one....

I think literally it's kind of ridiculous, but metaphorically is quite interesting.

You might consider a realization of 'keeping secret' as an impermeable (or maybe semi-permeable) boundary -- you control what gets out. And from that perspective, the integrity of boundaries is what makes physical (or ideological) integrity possible: within this boundary is me; outside of this boundary is not me.

This is literally the case from a cellular / physiological perspective, although even there, if you zoom in, you see an incredible dance, where blurring the line between me and not me is what makes life possible. Certainly, at a higher level, it's what makes life interesting.

If we erase this distinction, what's left? Only entropy.

Yeah, I don't see it either.

Even on a fully public life, people will be different.

The thing about privacy is that you have the ability to present different parts of yourself to different people. You behave one way with your boss, and another way with your family for example.

Nice call out. Never considered this aspect of secrecy but I can kind of see it but would also be interested in possible reasonings.

A secret can be seen as hidden state so if as a person, you have no hidden state then perhaps in an operational sense, you're replaceable. There is plenty of hidden state however that isn't classified as a secret. Say you know a system better than anyone else. That knowledge may not be secret so much as inconvenient for others to obtain. Maybe that disproves the statement since non-secrets can still distinguish.