This is certainly an interesting idea, but is there a body of research behind it? (How does one prove that anxiety is caused by "existential suffering" anyway?)

This is certainly an interesting idea, but is there a body of research behind it? (How does one prove that anxiety is caused by "existential suffering" anyway?) What is the amount and quality of that research? Even if CBT is flawed it has an established track record of clinical success so I still think it should be regarded as a "tool in the box."