Why does everyone say not to study for the CIRE like it's the CSC?

The difference is what the exam asks you to do. The CSC tested knowledge in isolation — define suitability, list the elements of KYC, what's a bond yield. You could study a topic, answer questions about that topic, and move on. The CIRE almost never asks you to define anything. It hands you a client scenario where someone wants something that might be unsuitable, might violate firm policy, or might be fine depending on details you have to infer — then gives you four answers that all sound defensible and asks for the best one. That's a judgment skill, not a recall skill.

This is why people who crushed the CSC still fail the CIRE: they read the material, memorize the key points, do a few practice questions, then sit an exam that never tests memorization. What actually transfers is volume — working through hundreds of scenarios until you start recognizing the trap before you finish reading the question. And study your wrong answers harder than your right ones; the wrong answers are where your blind spots hide, and your blind spots are what cost you on exam day.