Passphrases are a great evolutionary step from passwords. They can be extremely complicated, yet easy to remember and convenient to use. They are super hard for a hacker to crack/snoop since the hacker cannot brute force, use dictionary words, peep while you type on the keyboard or even use a keylogger (techically possible, but makes it harder).

But then passphrases are yet to catch up with many users coz of awareness. Here is a wonderful article from Okta on Passwords vs Passphrases. 

Then again the strength & usefulness of passphrases is in the hands of the users, the weakest link in security.