Sometimes face to face therapy can depend on whether the patient and therapist have a good ‘alliance’ with each other. For various reasons this doesn’t always happen.
Also some therapists know the ‘theory’ very well but maybe don’t have any real experience of severe anxiety or panic attacks.
The therapist who takes you through CBT4PANIC has suffered from panic disorder himself so he is able to understand the problem at a deeper level than most therapists.
Online programes can also be more effective because you get to work at your own pace in your own time.