You rely on one of several central authorities to grant a user access to your website (or be faced with a scary message about your site being insecure). Just b

You rely on one of several central authorities to grant a user access to your website (or be faced with a scary message about your site being insecure). Just because you can choose from one of several central authorities doesn't change the fact that you are reliant on them to authorize the user's ability to establish a network connection with you.