What you're trusting the browser for there is the extra protection that preloading provides, but that's not the whole benefit here. The larger benefit is that it makes it infeasible for services to neglect to support HTTPS. So, even if your browser's preload list is busted, the site will be guaranteed to support HTTPS because of this effort, which you'll still benefit from.
Ah ok. I think I see what you are saying now. As long as a sizeable portion of browsers support a fresh version of the preloaded list, there is sufficient customer feedback to push the servers to only support https. Right?
