But how do you know, that if kroah.com would use Let's Encrypt it would belong to Greg K-H? What if his true WEB-site would be e.g. greg-k-h.com?
Right. Also, when it comes to the other aspects of TLS, such as preventing middlemen from making sense of what information flows between you and the server, what exactly is the threat in this case? I mean, it's a public blog post, which you only ask to read and so you are served.