HTTPS may not be proprietary, but it comes with many of the same drawbacks: central control, lack of transparency, more difficult to debug, and less accessible in many circumstances.
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.