Sort of, that's conflating all free SSL certs with self signed certs. The whole point of an SSL cert is to provide authentication that the server you're talking

Sort of, that's conflating all free SSL certs with self signed certs. The whole point of an SSL cert is to provide authentication that the server you're talking to is really the server you were trying to reach at www.example.com . They are talking about self signed certificates which is basically the remote server saying "I'm www.example.com, you can trust me because I said so". Let's Encrypt is the same as other CAs out there in terms of authentication. In fact, if you see a certificate that's signed by Symantec, it's more likely to be mississued than a certificate signed by Let's Encrypt.