Thus, to evaluate any testing strategy, you cannot just evaluate how it finds bugs. You also must evaluate how it enables developers to fix (and even prevent) bugs.
Via: http://googletesting.blogspot.co.uk/2015/04/just-say-no-to-more-end-to-end-tests.html
Of course, J. B. Rainsberger has been saying this for years. But it’s nice to see Google reinforcing it.