The authority who grants you your SSL certificate. There is more than one out there, sure, but you can't do it without them. And ultimately, they all answer to

The authority who grants you your SSL certificate. There is more than one out there, sure, but you can't do it without them. And ultimately, they all answer to the same authority above them: the browser maker who populates the root trust store. So, to summarize: one more way for the browser maker to control what the user can and cannot access without jumping through hoops.