The credit agencies, without any legal rationale for doing so as far as I am aware, started to simply ignore letters which they believed were being generated in an automatic fashion. The decision tree is still the same -- it's the law! -- but to be effective at using it you have to phrase your request in a way which doesn't suggest that you are an expert at writing that request (unless you are a lawyer).
The chief objection to decision-trees-as-a-business-model seems to be that the credit dispute industry was crooked-as-a-barrel-of-fishhooks (welcome to consumer credit, hope you enjoy your stay) and successful in getting people to accept terms like "Pay me $2,000 and I will successfully get you off the hook of $8,000 in debt. Although not particularly relevant to you, this will require writing three letters and waiting a bit."