Your premise is fundamentally flawed if you're using "functional tests" as a technical term (cucumber is not a functional testing tool) and just wrong if you're

Your premise is fundamentally flawed if you're using "functional tests" as a technical term (cucumber is not a functional testing tool) and just wrong if you're using it as a descriptor. Just because you've seen people try and fail to use cucumber effectively doesn't mean it can't be done. I would go so far as to say if you can't do it, you should reexamine how both how you're writing your tests, and how you're writing your application.