[raxxorrax]

Also it is a moving space. Browsers don't accept a single certificate for a site anymore, you also have to have that signed by a CA. You can create such a certificate yourself too, but as of today you will need at least two certificates for browsers to fully accept a TLS secured connection. It hasn't been that long since that rule is in place.

So it isn't only the technicalities of asynchronous encryption, there is also specific behavior of applications that use certificates to prove identities.