Authenticity indeed is only guaranteed if you trust the CAs. Though it is still nice to know that getting a false cert isn't trivial. However, message integrit

Authenticity indeed is only guaranteed if you trust the CAs. Though it is still nice to know that getting a false cert isn't trivial. However, message integrity is a real benefit of SSL that doesn't need CAs. Consider the original article. In this case encryption doesn't matter and integrity does. Without message integrity, considering the login link has a known location and value, using bit-flips one might be able to change the login link (depending on the kind of encryption used). This message integrity is getting to be a much more important part of https. There are a lot of things that you don't want other parties able to change. Maybe even more things than you don't want them to be able to read.