While I was reading about Burmese names, I also learned that people in Burma can change their names pretty much at will, so even the idea that a name is a stable identifier for a person is not necessarily true, not to mention the whole legal name change thing or the common practice in many Western countries of women taking there husband’s name at marriage. I remember as a kid seeing occasional pieces of mail addressed to my mom under her maiden name even though she had been married for 15 or so years at that point. (Then there was the mail that I occasionally got addressed to “Donald Lopez” thanks to badly written code misparsing the joint ownership of the home I owned with my wife before the divorce.)

A "John Doe" [1] presumably still has a name, even if it's unknown to you specifically. That would be a counter-example to "You always know a person's name", not to "People have names".

[1] https://en.wikipedia.org/wiki/John_Doe