My source is self :) It’s inspired from books and concepts in the field of copywriting.

For instance, this book (no affiliate link): https://www.amazon.com/Phrases-That-Sell-Ultimate-Products/d...

And this article uses similar language: https://www.verticalresponse.com/blog/20-powerful-marketing-...

Is your point that I should have first defined “power phrase”? Or cited a source? I’m not familiar with appropriate convention.