> If I trust news.ycombinator.com because I trust ISRG Root X1, I might similarly trust John Doe's iPhone because I trust the government of France's CA, as a hypothetical, as long as the certification chain is valid there.

There are a whole ton of privacy problems with this. I am happy to demonstrate anonymously that I am not a bot, but a random blogger does not need to know that I am John Doe, a citizen of France with national ID number 12345678.