'Taken too far or used in the wrong context' - sure. In the language of this article, banking app users are mostly all 'high intent'. But that doesn't mean you

'Taken too far or used in the wrong context' - sure. In the language of this article, banking app users are mostly all 'high intent'. But that doesn't mean you can't evaluate criteria other than users who completed the workflow to determine what is a design improvement. You can still measure time to completion, how long it took the user from entering the workflow to completing a given task as a measure, and play with the design. Optimize the things users are doing the most, that sort of thing. A/B testing can help you there. It's not the be all end all; you still need sound UX design to figure out what designs to test out, but it can give you measurable data as to what works, rather than just UX gut feeling, or purely lab based results which don't reflect reality.