I worked for an authority that issued digital certificates for SSL and digital signatures. It's not only about providing encryption but also about trust, when a top level entity issues a SSL certificate, a number of identity validations are carried out, adding an extra layer or confidence on that website.

This may seem inconsequential for static websites without PII, however most browsers consider it important as it reduces the risk for all parties involved when encrypted communication is used and the content providers has taken basic steps for Identity verification.

There are logic flaws with this approach to security imo, but it's the most commonly used technique at the moment.