You forget a necessary step.
It is easy to forget a fundamental part of agile acceptance testing. It is the understanding of the story. I saw a video blog from Jeff Patton in which he mention that people tend to forget a step in user story acceptance testing. It are acceptance test! This implies you understand the story what needs to be created. The acceptance criteria are a subset of the understanding of the story, the conformation. Which in most cases are specification by examples.
What will happen if you forget the conversation about the user story and only focus on the examples.
My personal opinion is that it maybe looking like your doing something like ATDD but it is just not right. The power is that you combine the human factor in the conversation together with the agreement on when to accept the user story. This agreement can be perfectly captured in the examples. While exploring the specification by examples you discover new requirements that can only be successful if you understand what the goal of the user story is. Combining the acceptance testing with decent exploratory testing will get the job done.
Examples can not be the only agreement to develop a user story!